EP4263728A1 - Anwendungen, verfahren und werkzeuge zur entwicklung, schnellen herstellung und abscheidung einer nanokompositbeschichtung auf oberflächen für diagnosevorrichtungen mit elektrochemischen sensoren - Google Patents

Anwendungen, verfahren und werkzeuge zur entwicklung, schnellen herstellung und abscheidung einer nanokompositbeschichtung auf oberflächen für diagnosevorrichtungen mit elektrochemischen sensoren

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Publication number
EP4263728A1
EP4263728A1 EP21907436.6A EP21907436A EP4263728A1 EP 4263728 A1 EP4263728 A1 EP 4263728A1 EP 21907436 A EP21907436 A EP 21907436A EP 4263728 A1 EP4263728 A1 EP 4263728A1
Authority
EP
European Patent Office
Prior art keywords
coating
substrate
implementations
bsa
shows
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21907436.6A
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English (en)
French (fr)
Inventor
Pawan JOLLY
Sanjay Sharma TIMILSINA
Nolan DURR
Donald E. Ingber
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Harvard College
Original Assignee
Harvard College
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Filing date
Publication date
Application filed by Harvard College filed Critical Harvard College
Publication of EP4263728A1 publication Critical patent/EP4263728A1/de
Pending legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/24—Electrically-conducting paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D189/00—Coating compositions based on proteins; Coating compositions based on derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/16—Antifouling paints; Underwater paints
    • C09D5/1687—Use of special additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
    • G01N33/54366—Apparatus specially adapted for solid-phase testing
    • G01N33/54373—Apparatus specially adapted for solid-phase testing involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
    • G01N33/54366—Apparatus specially adapted for solid-phase testing
    • G01N33/54373—Apparatus specially adapted for solid-phase testing involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
    • G01N33/5438—Electrodes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
    • G01N33/54393—Improving reaction conditions or stability, e.g. by coating or irradiation of surface, by reduction of non-specific binding, by promotion of specific binding
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
    • G01N27/327—Biochemical electrodes, e.g. electrical or mechanical details for in vitro measurements
    • G01N27/3275—Sensing specific biomolecules, e.g. nucleic acid strands, based on an electrode surface reaction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
    • G01N27/4145—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for biomolecules, e.g. gate electrode with immobilised receptors

Definitions

  • This invention relates to compositions and methods for making anti-fouling and electrically responsive coatings. The rapid preparation of the coatings is also described.
  • BSA Bovine Serum Albumin
  • PEG poly(ethylene glycol) polymers
  • the blockers do not interfere with the final measurement. This is because the assay chemistry and measurements are fully decoupled.
  • the assay is carried out on a surface (e.g. plates, microbeads and nanoparticles) whereas the final measurement is performed using an external transducer.
  • a surface e.g. plates, microbeads and nanoparticles
  • the final measurement is performed using an external transducer.
  • fluorescence based assays light of a predetermined wavelength is shined on a surface bearing the capture agent and the light emitted is quantified by a photodiode or CCD sensor (i.e., the transducer).
  • the surface where the molecular interaction takes place acts as a passive support and does not contribute to the measurement.
  • the capture agent is typically immobilized at the surface of the transducer using strategies that should maximize its density and orientation, prevent non-specific interactions, and at the same time, preserve the ability of the electrode to record electrochemical signals with high sensitivity. Accordingly, it is imperative to the development of these electrochemical sensors that its surface resists biofouling, the aggregation of biomolecules on the surface, and that it maintains its initial physical and/or chemical properties (e.g. conductivity).
  • the standard process to functionalize transducers with an anti-fouling coating is to drop cast a composition on the surface of the transducer and incubating overnight. This step adds a day to the process and thus lengthens the time to make the final sensors. Integration into a multi-step on continuous manufacturing process may be frustrated, since the coating step may constitute a bottleneck to the entire process.
  • the inventions described herein relate to compositions and their application to transducer surfaces.
  • the coatings protect these surfaces from unwanted interactions that impede or diminish their intended function.
  • the coatings can be applied to electrodes and gates of bio-Field Effect Transistors (bio-FET), providing electrical transducers that can be utilized in complex matrices such as blood and plasma.
  • bio-FET bio-Field Effect Transistors
  • implementations described herein are amenable to continuous processes such as reel to reel manufacturing, allowing large scale commercialization of devices using the coatings.
  • a method for making a coating on a surface of a substrate includes applying a mixture to a surface of a substrate while maintaining the substrate at an elevated temperature, wherein the mixture comprises a particulate material and a proteinaceous material.
  • the mixture further comprises a cross-linking agent.
  • the proteinaceous material includes a cross linking agent attached to or as part of the proteinaceous material’s structure.
  • the elevated temperature is maintained for at least 10 seconds and less than two minutes.
  • the elevated temperature is at least 50 °C.
  • the method further comprises denaturing the proteinaceous material.
  • optionally said denaturing the proteinaceous material is: prior to mixing the proteinaceous material with the particulate material; and/or after applying the mixture to the substrate.
  • the substrate is particle, a nano-particle, a micro-particle, a nano-fiber, a micro-fiber, a flake, a chip, a crystal, a porous substrate, a wafer, a wire, a nano-wire, a micro-wire, a channel, a nano-channel, a micro-channel, a rod, a nano-rod, a micro-rod, a foil, a sheet, a web, or combination of these forms.
  • the substrate includes a material selected from the group consisting of metals, polymers, carbon based materials, ceramics, glass and any combinations thereof.
  • the substrate includes gold.
  • the substrate includes graphite, diamond, glassy carbon, or carbon nano-tubes.
  • the substrate includes an organic polymer.
  • the particulate material is a rod, fiber, a particle, a flake or combinations of these.
  • the particulate material is a dielectric.
  • the particulate material is a conductor or semi-conductor.
  • the particulate material comprises an allotrope of carbon atoms arranged in a hexagonal lattice.
  • the method includes applying a layer of a second substrate on the coating of proteinaceous material and optionally coating a second mixture comprising a second mixture and second proteinaceous material on the second substrate, providing a layered material having alternating layers of substrate and proteinaceous/particulate material.
  • the method further comprises a step of pre-treating the substrate prior to applying the mixture.
  • applying the mixture comprises spraying, spin coating, dip coating, inkjet printing, 3-D printing, vapor deposition, painting, and/or drop casting.
  • the method is a continuous process or semi-continuous process.
  • the method further comprises denaturing the proteinaceous material and subsequently adding a temperature sensitive material to the mixture prior to coating the substrate.
  • the substrate surface defines a channel or chamber, such as a channel in or chamber in a microfluidic device.
  • the substrate is a micro/nano gap devices where the coating can enable higher sensitivity and the coating can either be used to coat the surfaces of a gap in the micro/nano gap device, or the coating is applied for surface modification to enable linking of specific probes and antifouling properties.
  • a substrate including a coating on a surface thereof, wherein said coating is applied using a method described herein.
  • the substrate is an electrode, a capacitor, a bio-Field Effect Transistor (bio-FET), a transistor, or an optical device.
  • bio-FET bio-Field Effect Transistor
  • a capacitor including a dielectric material dispersed in a denatured and cross-linked proteinaceous material, and covering a conductive substrate.
  • a bio-FET comprising a composition including a particulate material dispersed in a denatured proteinaceous material and coating at least a portion of a transistor.
  • the compositing is coated on a gate of the bio-FET.
  • FIG. 1 depicts a cyclic voltammetry measurement of the biosensor made using different coating deposition times, according to some implementations.
  • FIG. 2 is a plot of BSA concentration data for an anti-fouling coating, according to some implementations.
  • FIG. 3 is a plot of glutaraldehyde concentration data for an anti-fouling coating, according to some implementations.
  • FIG. 4 is a plot of a functionalized graphene oxide concentration data for an antifouling coating, according to some implementations.
  • FIG. 5 is a plot comparing coating methods, according to some implementations.
  • FIG. 6 is a plot comparing coating methods with a NT-proBNP assay, according to some implementations.
  • FIG. 7 shows a 3D schematic of and electrode with antifouling nanocomposite, according to some implementations.
  • FIG. 8 is a plot showing electrochemical characterization of a coating, according to some implementations.
  • FIG. 9A and FIG. 9B are CV plots showing oxidation and reduction peaks of ferri- /ferrocyanide, according to some implementations.
  • FIG. 9A dipping in water at room temperature and,
  • FIG. 9B cooling to room temperature before dipping.
  • FIG. 10 is a plot showing optimization of coating time for sensors, according to some implementations.
  • FIG. 11 is a plot showing optimization of a coating including reduced Graphene oxide (rGOx), according to some implementations.
  • FIG. 12 is aplot showing optimization of BSA for a coating composition, according to some implementations.
  • FIG. 13 A is an optimization plot for rGOx, according to some implementations.
  • FIG. 13B shows a Cyclic Voltammogram (CV) showing oxidation and reduction peaks of ferri-/ferrocyanide of various nanocomposite-coated electrodes, according to some implementations
  • FIG. 14 is a plot showing electrochemical characterization of various electrode coatings, according to some implementations.
  • FIG. 15 shows CVs of bare gold- (left) and coated gold electrodes (right) of an of ferri-/ferrocyanide at different scan rates, according to some implementations.
  • FIG. 16 shows a plot of extracted oxidation/reduction peak current (ip) mean values derived from the CV scans shown in FIG. 15 plotted versus the square root of the scan rate, according to some implementations.
  • FIG. 17 shows a plotted comparison of antifouling activity with mean value of current density recorded at bare gold electrodes and Gold electrodes with antifouling coating stored for 9 weeks at 4 °C in 1% BSA and unprocessed human plasma, according to some implementations.
  • FIG. 18A and FIG. 18B are plots characterizing the antifouling nanocomposite coating, according to some implementations.
  • Bar graph (FIG. 18A) shows current density of fresh sensors (black bar) and sensors after 1 hour in varying biofluids: whole blood, saliva, and urine (grey bar).
  • UV absorption spectra (FIG. 18B) of BSA when mixed with/without GA and/or GOx. a.u., arbitrary units.
  • FIG. 19A-19E are scanning electron micrograph of the bare Gold (FIG. 19 A, FIG. 19D), Gold/BSA/GOx (FIG. 19B), and Gold/BSA/GOx/GA (anti-fouling coating) (FIG. 19C, FIG. 19E), according to some implementations.
  • FIG. 20A shows a 3D image of roughness for a bare gold electrode
  • FIG. 20B shows a 3D image of coated gold electrode, according to some implementations.
  • FIG. 20C-20H show TEM images of bare gold (FIG. 20C, FIG. 20F), coated gold electrode with top Iridium layer (FIG. 20D, FIG. 20G), and without top Iridium layer (FIG. 20E, FIG. 20H) for better contrast.
  • FIG. 21A-21B show AFM 2D (FIG. 21A) and 3D (FIG. 21B) survey images of bare gold electrode, according to some implementations.
  • FIG. 21C-21D show AFM 2D (FIG. 21C) and 3D (FIG. 21D) survey images of gold electrode with antifouling coating, according to some implementations.
  • FIG. 22 shows an XPS spectra for gold electrode coated with antifouling coating, according to some implementations.
  • FIG. 23 A-23L depict the characterization of the antifouling nanocomposite coating.
  • XPS X-ray Photoelectron Spectroscopy
  • FIG. 24A-24G show schematics and calibration curves for MI and TBI biomarkers using EC-biosensors and 96 well plate.
  • FIG. 24A shows a schematic for the preparation and assay steps for the EC-Biosensor.
  • FIG. 24B-24G are calibration curves for different biomarkers including (24B) cardiac troponin I (cTnl); (24C) B-type natriuretic peptide (BNP); (24D) N-terminal (NT)- pro hormone BNP (NT -proBNP); (24E) cardiac troponin ITC complex (cTnITC); and (24F) Glial fibrillary acidic protein (GFAP).
  • FIG. 25A-25F are images of a drop on a chip for contact angle measurements.
  • FIG. 25A is an uncleaned chip with protective organic layer.
  • FIG. 25B is a chip cleaned with acetone and Isopropyl alcohol.
  • FIG. 25C is a plasma treated chip.
  • FIG. 25D is a plasma-treated chips with BSA coating.
  • FIG. 25E is a plasma-treated chip with BSA and GOx coating.
  • FIG. 25F is a plasma- treated chips with antifouling nanocomposite coating.
  • FIG. 26A-26C illustrates optimization and two-step assay for different biomarkers.
  • FIG. 26A shows optimization of detection antibody for the assay of cTnl.
  • FIG. 26B is a calibration curve of cTnl.
  • FIG. 26C is a calibration curve of NT-proBNP.
  • FIG. 27A-27G illustrates assay development and optimization for single step assay for different biomarkers.
  • FIG. 27A shows optimization of cTnl capture antibody.
  • FIG. 27B shows optimization of cTnl detection antibody.
  • FIG. 27C shows optimization of HRP-Streptavidin.
  • FIG. 27D shows optimization of TMB incubation time.
  • FIG. 27E shows optimization of BNP detection antibody.
  • FIG. 27F shows optimization of NT-proBNP detection antibody.
  • FIG. 27G shows optimization of cTnITC detection antibody.
  • FIG. 27H-27J illustrate cross-reactivity test of the EC Biosensor. CV oxidation and reduction peaks of uric acid (FIG. 27H), Dopamine (FIG. 271), and Tryptophan (FIG. 27J) are depicted.
  • FIG. 28A-28F shows characterization and stability of antifouling nanocomposite and precipitated TMB.
  • FIG. 28A shows an assay of NT -proBNP.
  • FIG. 28B depicts a comparison of rapid versus 24h coating for assay of cTnl.
  • FIG. 28C shows stability of precipitated TMB for detection of cTnITC.
  • FIG. 28D shows stability of precipitated TMB for detection of GFAP.
  • FIG. 28E shows stability of coating solution stored at 4 degrees.
  • FIG. 28F shows stability of coating solution stored at room temperature.
  • FIG. 29A-29E illustrates the specificity and Multiplexed detection for MI and TBI Biomarkers using EC-Biosensors.
  • FIG. 29A shows a schematic for multiplexed detection on the EC-Biosensor showing detection of four biomarkers in a single EC-Biosensor.
  • FIG. 29A shows a schematic for multiplexed detection on the EC-Biosensor showing detection of four biomarkers in a single EC-Biosensor.
  • FIG. 29B shows specificity and cross-reactivity of BNP antigen against different capture antibodies (anti-cTnITC, anti -NT -proBNP, anti-GFAP, and anti-S-lOOb) and detection antibodies (anti-cTnITC, anti -NT - proBNP, anti-GFAP, and anti-S-lOOb) along with specific detection with anti -BNP capture and detection antibody at different concentrations of BNP done in 96 well plate.
  • FIG. 29C shows a calibration curve for multiplex detection of cTnITC on the EC-Biosensor with four different capture antibodies on each electrode (anti-cTnITC, anti-S-lOOb, anti-GFAP, and anti-NT-proBNP).
  • FIG. 29D shows a calibration curve for multiplex detection of increasing concentrations of cTnITC (left y-axis) and decreasing concentrations of GFAP (right y-axis) on the EC-Biosensor with four different capture antibodies on each electrode.
  • FIG. 29E shows a calibration curve for multiplex detection of increasing concentrations of cTnITC and S-lOOb (left y-axis) and decreasing concentrations of GFAP and NT -proBNP (right y-axis) on the EC-Biosensor with four different capture antibodies on each electrode.
  • FIG. 30A-30H illustrates microfluidic integration and clinical validation of the assay.
  • FIG. 30A is a picture of a microfluidic device where six EC-Biosensors can be placed to run the assay in parallel.
  • FIG. 30B is a 3D schematic of the microfluidic channels and their interface with the EC-Biosensor.
  • FIG. 30C shows a calibration curve for the assay of cTnITC performed on the microfluidic platform with reduced assay time using spiked plasma samples.
  • FIG. 30D shows a calibration curve for the assay of GFAP performed on the microfluidic platform using spiked plasma samples.
  • FIG. 31A-31F illustrates an assay of different biomarkers on EC-Biosensor. TMB oxidation and reduction peaks obtained with a CV on EC Biosensors with antifouling coating for detection of different concentrations of biomarkers of Myocardial infarction and Traumatic Brain Injury.
  • FIG. 31A shows BNP
  • FIG. 3 IB shows NT-proBNP
  • FIG. 31C shows cTnl
  • FIG. 3 ID shows cTnITC
  • FIG. 3 IE shows GFAP
  • FIG. 3 IF shows SI 00b.
  • FIG. 32A depicts a calibration curve of cTnITC
  • FIG. 32B depicts a calibration curve of GFAP
  • FIG. 32C depicts multiplex detection of cTnITC and GFAP on EC Biosensor with four different capture antibodies on each electrode.
  • FIG. 33A-33C illustrate the specificity and cross-reactivity test for different biomarkers of MI and TBI done in 96 well plate.
  • FIG. 33A shows the specificity and crossreactivity of NT-proBNP antigen against different capture antibody and detection antibody.
  • FIG. 33B shows the specificity and cross-reactivity of GFAP antigen against different capture antibody and detection antibody.
  • FIG. 33C shows the specificity and cross-reactivity of S-lOOb antigen against different capture antibodies and detection antibody.
  • FIG. 34A-34D illustrates a specificity and cross-reactivity test for different Troponin antibody pair and antigen done in 96 well plate.
  • FIG. 34A shows specificity and crossreactivity of cTnITC antigen against different capture antibody and detection antibodies.
  • FIG. 34B shows specificity and cross-reactivity of cTnl antigen against different capture antibodies and detection antibodies.
  • FIG. 34C shows specificity and cross-reactivity of cTnITC antigen against different capture antibody and detection antibody.
  • FIG. 34D shows specificity and cross-reactivity of cTnl antigen against different capture antibodies and detection antibodies.
  • the methods, compositions and structures provided herein are based in part on the preparation of protective coatings on substrate surfaces.
  • the coatings include conductive or non- conductive particulate materials in a proteinaceous matrix that can be rapidly formed on surfaces.
  • the proteinaceous material is rapidly denatured and cross-linked, forming a robust protective coating on electric transducers or forming a part of an electric transducer.
  • the methods and compositions can be implemented for large scale manufacturing as well as small laboratory scale and rapid small scale prototyping.
  • the invention includes the preparation of an electrochemically active surface blocker that can prevent non-specific interaction while keeping an electric transducer active.
  • an “electric transducer” is a device that interacts with a molecule, polymer, biological materials to provide an electrical signal. The signal can include, for example, a change in current, a change in voltage, a change in capacitance, a change in impedance, or a change in dielectric constant.
  • the electric transducer is a biotransducer, such as an electrochemical transducer, an optical transducer, a bio-FET, or a piezoelectric biotransducer.
  • the electric transducer is an electrode.
  • the methods include coating a surface of a substrate while maintaining the surface of the substrate at an elevated temperature.
  • an “elevated temperature” is a temperature above the ambient temperature, such as above room temperature.
  • the temperature can be above about 50 °C (e.g. above, 60, 70, 80, 90 or 100 °C).
  • the elevated temperature is below about 180 °C (e.g., below about, 140, 130, 120, 110, or 100 °C).
  • the elevated temperature is between about 60 and 110 °C, between about 70 and 100 °C, between about 80 and 90 °C, such as about 85 °C.
  • the temperature can be maintained by any method.
  • the substrate is place on a hot temperature controlled surface such as a hot plate.
  • the heating is provided in an oven or hot air.
  • UV light is used for heating the substrate directly on the surface to be coated, or on an opposite surface or area of the substrate.
  • the substrate is immersed in a heated solution, such as including the coating composition.
  • the temperature is maintained for any amount of time to provide a robust surface coating.
  • the temperature is maintained for less than about 24 hours, less than about 12 hours, less than about 6 hours, less than about one hour, less than about 30 minutes, less than about 10 minutes, less than about two minutes, or less than about a minute.
  • the temperature is maintained for at least about 1 second, at least about 5 seconds, at least about 10 seconds, at least about 30 seconds, at least about 40 seconds, at least about 45 seconds.
  • the method includes coating the surface of the substrate with a mixture that includes a particulate material and a proteinaceous material.
  • the proteinaceous material includes a cross-linking agent attached to or as part of the structure of the proteinaceous material.
  • a cross-linking agent is added to the mixture. Without ascribing to a specific mechanism, the elevated temperature and time is used at least in part to modulate the amount of cross linking that occurs. The heating can also denature the proteinaceous material.
  • the mixture is heated to an elevated temperature prior to coating on the surface. In some implementations, the mixture is heated to an elevated temperature that is different than the elevated temperature to which the substrate is heated. In addition to heating, in some implementations, the mixture is homogenized, before or after it is heated. For example, the mixture can be sonicated before addition to the substrate.
  • to cross link means to form one or more bonds between polymer chains so as to form a network structure such as a gel or hydrogel.
  • the polymers are then “crosslinked” polymers. The bonding can be through hydrogen bonding, covalent bonding or electrostatic.
  • the “cross linking agent” can be a bridging molecule or ion, or it can be a reactive species such as an acid, a base or a radical producing agent.
  • the cross linking agents contain at least two reactive groups that are reactive towards numerous groups, including primary amines, carboxyls, sulfhydryls, carbohydrates and carboxylic acids. Proteins and peptide molecules have many of these functional groups and therefore proteins and peptides can be readily conjugated and cross-linked using these cross linking agents.
  • Cross linking agents can be homobifunctional, having two reactive ends that are identical, or heterobifunctional, having two different reactive ends.
  • the cross linking agent is a molecule such as glutaraldehyde, dimethyl adipimidate (DMA), dimethyl suberimidate (DMS), Bissulfosuccinimidyl suberate, formaldehyde, p-azidobenzoyl hydrazide; n-5-azido-2-nitrobenzoyloxysuccinimide; n-[4-(p- azidosalicylamido)butyl]-3'-(2'-pyridyldithio) propionamide; p-azidophenyl glyoxal monohydrate; bis [b-(4-azidosalicylamido)ethyl]disulfide; bis [2-(succinimidooxycarbonyloxy)ethyl] sulfone; 1,4-di [3'-(2'-pyridyldithio)propionamido] butane;
  • the cross linking agent is mone- or poly-ethylene glycol diglycidil ether.
  • the cross linker is a homobifunctional cross linking agent such as glutaraldehyde.
  • proteinaceous material includes proteins and peptides, functionalized proteins, copolymers including proteins, natural and synthetic variants of these, and mixtures of these.
  • proteinaceous material can be Bovine Serum Albumin (BSA).
  • the proteinaceous material can include or be replace with any blocking agent.
  • a “blocking agent” or “molecular blockers” are compounds used to prevent non-specific interactions.
  • the blocking agent when coated on the substrate surface prevents non-specific interactions or fouling of the surface when it is contacted or immersed in a complex matrix.
  • the surface can include a capture agent, for example, directly attached to the surface or attached to the blocking agent.
  • Non-specific interactions can include any interaction that is not desired between the target molecule and the surface, or between other components in solution.
  • the blocking agent can be a protein, mixture of proteins, fragments of proteins, peptides or other compounds that can absorb to the surface of the substrate.
  • proteins e.g., BSA and Casein
  • poloxamers e.g., pluronics
  • PEG-based polymers and oligomers e.g., diethylene glycol dimethyl ether
  • cationic surfactants e.g., DOTAP, DOPE, DOTMA
  • Some other examples include commercially available blocking agent or components therein that are available from, for example, Rockland Inc.
  • BBS Fish Gel Concentrate such as : BBS Fish Gel Concentrate; PBS Fish Gel Concentrate; TBS Fish Gel Concentrate; Blocking Buffer for Fluorescent Western Blotting; BLOTTO; Bovine Serum Albumin (BSA); ELISA Microwell Blocking Buffer; Goat Serum; IPTG (isopropyl beta-D-thiogalactoside) Inducer; Normal Goat Serum (NGS); Normal Rabbit Serum; Normal Rat Serum; Normal Horse Serum; Normal Sheep Serum; Nitrophenyl phosphate buffer (NPP); and REVITABLOTTM Western Blot Stripping Buffer.
  • “denaturing” is the process of modifying the quaternary, tertiary and secondary molecular structure of a protein from its natural, original or native state. For example, such as by breaking weak bonds (e.g., hydrogen bonds), which are responsible for the highly ordered structure of the protein in its natural state.
  • the process can be accomplished by, for example: physical means, such as by heating, sonication or shearing; by chemical means such as acid, alkali, inorganic salts and organic solvents (e.g., alcohols, acetone or chloroform); and by radiation.
  • a denatured protein, such as an enzyme losses its original biological activity.
  • the denaturing process is reversible, such that the protein molecular structure is regained by the re-forming of the original bonding interactions at least to the degree that the original biological function of the protein is restored.
  • the denaturing process is irreversible or non-reversible, such that the original and biological function of the protein is not restored.
  • Cross-linking for example after denaturing, can reduce or eliminate the reversibility of the denaturing process.
  • the degree of denaturing can be expressed as a percent of protein molecules that have been denatured, such as a mole percent. Some methods of denaturing can be more efficient than others.
  • sonication applied to BSA can denature about 30-40% of the protein and the denaturing is reversible.
  • BSA When BSA is denatured it undergoes two structural stages. The first stage is reversible whilst the second stage is irreversible (e.g., non- reversible) but does not necessarily result in a complete destruction of the ordered structure. For example, heating up to 65°C can be regarded as the first stage, with subsequent heating above that as the second stage. At higher temperatures, further transformations are seen.
  • BSA is denatured by heating above about 65°C (e.g., above about 70°C, above about 80°C, above about 90°C, above about 100°C, above about 110°C, above about 120°C), below about 200°C (below about 190°C, 180°C, 170°C, 160°C, 150°C), and for at least about 1 minute (e.g., at least about 2, 3, 4, 5, 10 or 20 minutes) but less than about 24 hours (e.g., less than about 12, 10, 8, 6, 4, 2 1 hour).
  • the heating can include be included as a separate step to heating of the substrate and include different temperature ranges and heating times.
  • denaturing of the proteinaceous material can occur before deposition on the substrate surface. In some implementations, denaturing can occur only upon deposition on the substrate surface, for example when only a heating step to heat the substrate is included. In some implementations, denaturing occurs before and after deposition, for example, where heating occurs before and after deposition of the mixture on the substrate surface.
  • the proteinaceous material used in the compositions and structures described herein are at least about 20% to about 100% (e.g., 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%) denatured. In some embodiments, less than 50% of the denatured protein reverts back to its natural state (e.g., less than 40%, less than 30%, less than 20%, less than 10%, less than 1%).
  • the reversibility of the denaturing can be described as being 50% reversible, 40% reversible (60% irreversible), 30 % reversible (70% irreversible), 20% reversible (80% irreversible), 10% reversible (90% irreversible) or even 0% reversible (100% irreversible).
  • an agent is added after the denaturing and/or cross linking steps.
  • an agent is temperature sensitive but is needed in the surface coating.
  • the agent is a capture agent such as an enzyme or antibody that loses activity upon heating.
  • the particulate material is added after the denaturing and/or cross linking step.
  • the substrate can be in any form having a surface that can be coated.
  • the substrate can be included in the form of a particle, a nano-particle, a micro-particle, a nano- fiber, a micro-fiber, a flake, a chip, a crystal, a porous substrate, a wafer, a wire, a nano-wire, a micro-wire, a channel, a nano-channel, a micro-channel, a rod, a nano-rod, a micro-rod, a foil, a sheet, a web, or combination of these forms.
  • the substrate is part of a microfluidic device, such as a channel or chamber therein. In some implementations, the substrate is part of a micro well plate. In some implementation, the substrate is an optical fiber. In some implementations, the substrate is part of a mico or nano-gap device.
  • the substrate can be a transparent material, an opaque material, an insulator, a conductor, a semi-conductor, a dielectric material, or include a combination of these properties.
  • the substrate can be a transparent conductor such as indium tin oxide (ITO).
  • ITO indium tin oxide
  • the substrate is poly crystalline silicon, single crystal silicon, a doped silicon, a silicon oxide, a silicon nitride, a silicon oxnitride, a metal oxide, a metal nitride, or a metal oxynitride.
  • the substrate includes a metal, a metalloid, a polymer, a ceramic, a glassy material, an amorphous material, a biological membrane, a carbon based material, or any combination of these.
  • the substrate can include aluminum, copper, silver, gold, or platinum.
  • the substrate includes gold.
  • the substrate includes a silica based glass (e.g., pure silica or mixtures such as borosilicate glass).
  • the substrate includes graphite, diamond, glassy carbon, or carbon nano-tubes (CNTs).
  • the substrate is a chip including gold and a silica based glass.
  • the substrate includes one or more polymers.
  • the polymer is a natural polymer such as cellulose, natural silk, cotton, or natural rubbers.
  • the polymer is a synthetic polymer, such as nylon, epoxies, polyethylene (e.g. HDPE and LDPE), polypropylene, polybutadiene, polyethylene terephthalate (PET), polycarbonate, polyurethane, fluorinated polymers (e.g. TEFLON®), polystyrene (e.g. Styrofoam), sulfonated polystyrene, aramide (e.g.
  • the polymer is an ionic polymer, such as a cationic or anionic polymer.
  • the substrate or substrate surface is treated.
  • surfaces such as polymers (e.g. flexible substrates such as PET) may require additional modifications for the coating to adhere to the surface.
  • polyHEMA lacks functional groups and presents a challenge for adhesion.
  • one approach is to add an adherence layer such as a silane coupling layer on the polyHEMA surface which provides attachment of the protective coating through coupling chemistry.
  • the substrate is functionalized with cationic functional groups such as quaternary amines.
  • the substrate is functionalized with anionic groups, such as carboxylic acid groups.
  • the substrate is functionalized with hydrophobic groups such as hydrocarbons.
  • the substrate is functionalized with hydrophilic groups such as polyethylene oxide.
  • the surface is treated with silanes, functional groups for click chemistry, groups for avidin-biotin interaction, thiol groups, self-assembling monolayers, anionic polymerization groups, radical polymerization groups, salinization, esterification, pegylation, hydrosylation, UV treatment, ionizing radiation such as electron beam irradiation, ozone treatment, acid treatment, and plasma treatment.
  • the surface is treated with a cross-linking agent, such as the cross linking agents as previously described, where the cross linking agent can cross link to the surface (e.g. through surface functional groups and one group on the linking agent) and to the protein.
  • the particulate material can be in any form compatible with the proteinaceous material.
  • compatible means the particle does not degrade/destroy the proteinaceous material and the proteinaceous material does not degrade/destroy the particulate material.
  • the particulate material has a surface that can be coated with the proteinaceous material.
  • the particulate material can be included in the form of a particle, a nano-particle, a micro-particle, a nano-fiber, a micro-fiber, a flake, a chip, a crystal, a porous particle, a rod, a nano-rod, a micro-rod, or combination of these forms.
  • the particulate material can be a transparent material, an opaque material, an insulator, a conductor, a semi-conductor, a dielectric material, or include a combination of these properties.
  • the particulate material includes a metal, a metalloid, a polymer, a ceramic, a glassy material, an amorphous material, a biological particle, a protein particle, a micelle, a vesicle, a cell, a carbon based material, or any combination of these.
  • the particulate material can include aluminum, copper, silver, gold, or platinum.
  • the substrate includes a gold.
  • the particulate material includes a silica based glass (e.g., pure silica or mixtures such as borosilicate glass).
  • the particulate material includes graphite, graphene oxide, reduced graphene oxide, diamond, glassy carbon, or carbon nano-tubes (CNTs).
  • the particulate material includes one or more polymers.
  • the polymer is a natural polymer such as cellulose, natural silk, cotton, or natural rubbers.
  • the polymer is a synthetic polymer, such as nylon, epoxies, polyethylene (e.g. HDPE and LDPE), polypropylene, polybutadiene, polyethylene terephthalate (PET), polycarbonate, polyurethane, fluorinated polymers (e.g.
  • polystyrene e.g. Styrofoam
  • sulfonated polystyrene aramide (e.g. KEVLAR®)
  • poly acrylonitrile poly vinyl acetate, poly vinyl chloride (PVC), poly methyl methacrylate (PMMA), Polyhydroxyethylmethacrylate (PolyHEMA), poly ethers, poly lactic acid, and copolymers and blends of these.
  • the polymer is an ionic polymer, such as a cationic or anionic polymer.
  • the particulate material is surface treated.
  • surfaces such as polymers may require modifications for the proteinaceous material to mix well with the particulate material.
  • the particulate material is functionalized with cationic functional groups such as quaternary amines.
  • the particulate materials are functionalized with anionic groups, such as carboxylic acid groups.
  • the particulate materials are functionalized with hydrophobic groups such as hydrocarbons.
  • the particulate materials are functionalized with hydrophilic groups such as polyethylene oxide.
  • the coating on the substrate is composed of conducting particulate material such as a carbon allotrope (e.g., carbon nanotubes, graphene and/or reduced graphene oxide); and a denatured protein such s denatured BSA.
  • conducting particulate material such as a carbon allotrope (e.g., carbon nanotubes, graphene and/or reduced graphene oxide)
  • a denatured protein such as s denatured BSA.
  • a gold electrode that can be coated with the mixture, made with conducting particulate material and where the denatured protein is functionalized with a capture agent, such as a capture antibody.
  • the captured antigen such as an IL6, is detected with a biotinylated detection antibody conjugated to streptavi din-poly HRP.
  • the TMB Upon capture of the antigen, the TMB is oxidized, and precipitates onto the electrode surface where it can be detected electrochemically (e.g., by reduction, or reduction and oxidation cycles such as used in cyclic voltammetry).
  • the coating can be used to either (i) block an electrode already modified with a capture agent, or in some embodiments (ii) coat a clean electrode and later be modified with the capture agent.
  • a “capture agent” or “capture molecule” is a natural or synthetic receptor (e.g., a molecular receptor) that binds to a target molecule.
  • the capture agent is a “capture antibody.”
  • the binding is a specific binding such that it is selective to that target above non-targets.
  • the dissociation constant between the capture agent and target is at least about 200 nM, alternatively at least about 150 nM, alternatively at least about 100 nM, alternatively at least about 60 nM, alternatively at least about 50 nM, alternatively at least about 40 nM, alternatively at least about 30 nM, alternatively at least about 20 nM, alternatively at least about 10 nM, alternatively at least about 8 nM, alternatively at least about 6 nM, alternatively at least about 4 nM, alternatively at least about 2 nM, alternatively at least about 1 nM, or greater.
  • the specific binding refers to binding where the capture agent binds to its target without substantially binding to any other species in the sample/test solution.
  • a capture agent can be an antibody, adnectins, ankyrins, other antibody mimetics and other protein scaffolds, aptamers, nucleic acid (e.g., an RNA or DNA aptamer), protein, peptide, binding partner, oligosaccharides, polysaccharides, lipopolysaccharides, cellular metabolites, cells, viruses, subcellular particles, haptens, pharmacologically active substances, alkaloids, steroids, vitamins, amino acids, avimers, peptidomimetics, hormone receptors, cytokine receptors, synthetic receptors, sugars or molecularly imprinted polymer.
  • the capture agent is selective to a specific target or class of targets such as toxins and biomolecules.
  • targets such as toxins and biomolecules.
  • the target can be ions, molecules, oligomers, polymers, proteins, peptides, nucleic acids, toxins, biological threat agents such as spore, viral, cellular and protein toxins, carbohydrates (e.g., mono saccharides, disaccharides, oligosaccharides, polyols, and polysaccharides) and combinations of these (e.g., copolymers including these).
  • the capture agent is an antibody.
  • antibody and antibodies include polyclonal antibodies, monoclonal antibodies, humanized or chimeric antibodies, single chain Fv antibody fragments, Fab fragments, and F(ab)2 fragments.
  • Antibodies having specific binding affinity for a target of interest can be produced through standard methods.
  • the terms “antibody” and “antibodies” refer to intact antibody, or a binding fragment thereof that competes with the intact antibody for specific binding and includes chimeric, humanized, fully human, and bispecific antibodies.
  • binding fragments are produced by recombinant DNA techniques.
  • binding fragments are produced by enzymatic or chemical cleavage of intact antibodies. Binding fragments include, but are not limited to, Fab, Fab', F(ab')2, Fv, and single-chain antibodies.
  • the target of the capture agent can be redox active (e.g., an electroactive capture agent) and is directly detected by an electrode.
  • the capture agent facilitates detection of the target analyte by the electrode due to it concentrating the analyte near or at the surface of the electrode where it can be detected directly by electrochemical means.
  • the electrode is a gate electrode of a Field Effect Transistor (FET) and the change in concentration of the target of the capture agent changes the voltage in a range to activate/deactivate the gate.
  • FET Field Effect Transistor
  • the target is detected indirectly by electrochemical means.
  • the target can be detected by binding with a detection agent such as an antibody, protein or molecule that catalyzes, directly or indirectly, a redox reaction close to an electrode surface.
  • the detection agent, antibody, protein or molecule deposits a sacrificial redox active molecule on the electrode surface (e.g., on a coating that is on the metal surface of the electrode) that then is detected electrochemically.
  • the detection antibody can be conjugated with a redox catalyst and the sacrificial redox active molecule can be oxidized or reduced and precipitated onto the electrode surface.
  • the redox active catalyst is a peroxidase such as horseradish peroxidase (HRP) and the sacrificial redox active molecule is 3,3 ’-Diaminobenzidine (DMB); 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS); o-orthophenylenediamine (OPD); AmplexRed; 3, 3 '-Diaminobenzidine (DAB); 4- chloro-1 -naphthol (4CN); AEC; 3,3’,5,5’-Tetramethylbenzidine (TMB); homovanilllic acid; lumininol; Nitro blue tetrazolium (NBT); Hydroquinone; benzoquinone; mixtures of these; or mixtures of these.
  • Embodiments include known immunoassays or modifications of these to be detectable by electrochemistry.
  • the sacrificial molecule can also be detected by fluorescence.
  • the capture agent is used at a concentration between about 10 and about 5000 p/mL. In some implementations, the capture agent is used at a concentration between about 50 and 1000 p/mL, such as between about 100 and 1000 p/mL, or between about 100 and about 1000 p/mL. In some implementations, the detection agent is (e.g., detection antibody) is used at a concentration between about 0.1 and 100 p/mL, such as between about 0.5 and 50 p/mL, between about 1 and 20 p/mL, between about 1 and 8 p/mL, or between about 2 and 5 p/mL.
  • the detection agent e.g., detection antibody
  • the capture agent includes streptavidin-polyHRP or a similar molecule for signal augmentation.
  • the streptavidin-polyHRP concentration is between about 0.1 and about 100 p/mL, such as between about 0.5 and 50 p/mL, or between about 1 and 10 p/mL.
  • the ranges of concentrations of capture agent and detection agent can be used in any combination, such as 500 p/mL of capture agent in combination with 5 p/mL of detection agent.
  • the ranges of concentrations of capture agent, detection agent and streptavidin- polyHRP also be used in any combination, such as 500 p/mL of capture agent, 5 p/mL of detection agent and 2 p/mL streptavidin-polyHRP.
  • a “conductive surface” is an outer surface of a bulk conductive material.
  • any surface of a metal sheet, bar, wire, electrode, contact, etc. This can include porous materials, polished materials or materials with any surface roughness, surfaces that are substantially flat or have some curvature (e.g., concave or convex).
  • Conductive surfaces include surfaces of non-metallic materials that are poor conductors or good conductors, such as, for example graphite, Indium tin oxide (ITO), semiconductors, conductive polymers and materials used for making electrodes.
  • ITO Indium tin oxide
  • the conductivity can be in the range between a semiconductor (e.g., about IxlO 3 S/m) and a metal (e.g., about 5 x 10 7 S/m).
  • the conductive surface is the part of an electrode that is coated with a protective coating such as CNTs/BSA or rGO/BSA compositions, and then contact with the sample that is being probed for an electrochemical response.
  • the coated surface provides protection and anti-fouling properties to the surface of the substrate.
  • a complex matrix can include biomolecules, molecules, ions, cells, organisms, inorganic materials, liquids and tissue.
  • a complex matrix can include biological fluids; such as blood, serum, plasma, urine, saliva, interstitial fluid and cytosol; and tissues such as from a biopsy and tissues on a living organism (e.g., an implant, a diagnostic probe).
  • an “electrode” is a conductor through which current enters or leaves a medium, where the medium is nonmetallic.
  • the medium can be a complex matrix (e.g., blood or serum).
  • the electrode can be inserted into/onto a tissue such as mammalian tissue and be contacted with tissue and/or fluids therein/thereon.
  • the electrode can be large (e.g., with a working surface area of greater than 1 cm 2 , greater than 10 cm 2 , greater than 100 cm 2 ) or the electrode can be small (e.g., with a working surface area of less than 1 cm 2 , less than 1mm 2 , less than 100 pm 2 , less than 10 pm 2 , less than 1 pm 2 ).
  • the working surface area is the area in contact with the medium and wherein current enters or leaves the medium.
  • the electrode is a working electrode and the electrochemical cell can include a counter electrode and reference electrode.
  • the electric transducer such as an electrode
  • a “multiplexed” assay can be used to simultaneously measure multiple analytes or signals such as two or more (e.g., 3 or more, 5 or more, 10 or more, 50 or more, 100 or more, 1000 or more) during a single run or cycle of the assay.
  • the electric transducer can therefore be configured as an array of transducers, electrodes, microelectrodes or electrochemical sensors each of which can be independently electrically attached to a circuit for monitoring the electrical signals.
  • the array of electrodes can be disposed at the bottom, sides or top of a multiwell plate (e.g., microwell plate) arrayed on a flat surface such as a semiconductor chip (e.g., a sensor array chip) or form part of a multielectrode array (e.g., for connection of neurons to electronic circuitry).
  • the coatings can coat more than one sensor since the coating will not conduct between the sensors due to the anisotropy of the conduction, therefore an array of conductors, sensors or electrodes can be coated forming a multiplexed electrode.
  • Electric transducers can include materials with metallic conduction and semiconductors.
  • electric transducers can include metals, metal alloys, semiconductors, doped materials, conducting ceramics and conducting polymers.
  • electric transducer materials can include carbon (e.g., graphite, glassy carbon, conductive polymers), copper, titanium, brass, mercury, silver, platinum, palladium, gold, rhodium, zinc, lead, tin, iron, Indium Tin Oxide (ITO), silicon, doped silicon, II-VI semiconductors (e.g., ZnO, ZnS, CdSe), III-V semiconductors such as (e.g. GaAs, InSb), ceramics (e.g.
  • TiO2, FesO4, MgCr2O4 TiO2, FesO4, MgCr2O4, and conductive polymers
  • conductive polymers e.g., poly(acetylene)s, poly(p-phenylene vinylene), poly(fluorenes)s, polyphenylenes, polypyrenes, polyazulenes, polynaphthalenes, polyanilines, poly azepines, polyindoles, poly carbazoles, poly(pyrrole)s, poly(thiophene)s, and poly(3,4- ethylenedioxythiophene)), combinations, mixtures and alloys of these.
  • poly(acetylene)s poly(p-phenylene vinylene), poly(fluorenes)s, polyphenylenes, polypyrenes, polyazulenes, polynaphthalenes, polyanilines, poly azepines, polyindoles, poly carbazoles, poly(pyrrole)s,
  • the electric transducers are implemented to provide detection of an analyte using electrochemical methods.
  • Electrochemical methods are methods that rely on a change in the potential, charge or current to characterize the analyte’s chemical reactivity. Some examples include potentiometry, controlled current coulometry, controlled-potential coulometry, amperometry, stripping voltammetry, hydrodynamic voltammetry, polarography, stationary electrode voltammetry, pulsed polarography, electrochemical impedance spectroscopy and cyclic voltammetry.
  • the signals are detected using an electrode or electrochemical sensors coupled to circuits and systems for collection, manipulation and analysis of the signals.
  • carbon nanotubes and “graphene” are allotropes of carbon with sp 2 carbon atoms arranged in a hexagonal, honeycomb lattice.
  • Single layer graphene is a two- dimensional material, and is a single layer of graphite.
  • more than one layer of graphene can be referred to as graphene, for example between 1 and 200 layers (e.g., about 1 to 100 layers, about 1 to 50 layers, about 1 to 10 layers).
  • Carbon nanotubes are hollow, cylindrical structures, formed as a sheet of graphene rolled into a cylinder.
  • the allotropes of carbon can include some functionalization, such as oxygen, carboxylates, epoxides, amines, amides and combinations of these, as described below.
  • the functionalization includes poly amine functionalization such as pentaamine functionalization.
  • Graphene can be produced is high purity using chemical vapor deposition on clean metal surfaces and through exfoliation of pure graphite.
  • the exfoliation method of graphite includes using an adhesive which is pressed on the graphite surface repeatedly until a few or even one layer is obtained. These methods can be laborious and impractical, although they can produce graphene that is pure (e.g., greater than 99 wt.% carbon).
  • reduced graphene oxide rGO
  • rGO can be prepared more efficiently. In any case, both pure graphene and reduced graphene oxide can be used in embodiments for making non-fouling coatings.
  • graphene oxide is a material that can be formed from the oxidation of graphene or exfoliation of graphite oxide.
  • graphite is oxidized.
  • Hummers and Offeman method in which graphite is treated with a mixture of sulphuric acid, sodium nitrate and potassium permanganate (a very strong oxidizer).
  • Graphite oxide and graphene oxide are very similar, chemically, but structurally, they are very different. Both are compounds having carbon, oxygen and hydrogen in variable ratios. In the most oxidized state the oxygen amount can be as high as about 60 wt%. the amount of hydrogen varies depending on the functionalization, for example, the number of epoxy bridges, hydroxyl groups and carboxyl groups.
  • the main difference between graphite oxide and graphene oxide is the interplanar spacing between the individual atomic layers of the compounds, caused by water intercalation. This increased spacing, caused by the oxidisation process, also disrupts the sp 2 bonding network, meaning that both graphite oxide and graphene oxide are often described as electrical insulators.
  • Reduced graphene oxide is prepared from reduction of graphene oxide by thermal, chemical or electrical treatments. For example, treating the graphene oxide with; hydrazine, hydrogen plasma, heating in water, high temperature heating (e.g., under nitrogen/argon) and electrochemical reduction. Whereas graphene can be a single carbon layer ideally comprising only carbon, reduced graphene oxide is similar but contains some degree of oxygen functionalization. The amount of oxygen depends on the degree of reduction and in some materials can vary between about 50 wt% and about 1 wt. % (e.g., between about 30 wt.% and about 5 wt.%).
  • Reduced graphene oxide can be functionalized or include functional groups.
  • reduced graphene oxide often includes oxygen in the form of carboxyl groups and hydroxyl groups.
  • the carboxyl and hydroxyl groups populate the edges of the rGO sheets.
  • carbonylated reduced graphene oxide can refer to reduced graphene oxide having carboxyl groups.
  • the amount of oxygen attributable to the carboxyl groups is between about 30 wt.% and about 0.1 wt.% (e.g., between about 10 wt.% and about 1 wt.%).
  • Other forms of functionalization are possible.
  • amine functionalized rGO can be formed by a modified Buchere reaction, wherein ammonia an graphene oxide are reacted using a catalyst such as sodium bisulfite, or epoxide groups on graphene oxide can be opened with p- phenylenediamine.
  • the amount of nitrogen is between about 30 wt.% and 0.1 wt.% (e.g., between about 10 wt.% and 1 wt.%).
  • a polyamine is used to functionalize rGO.
  • pentaamine functionalized graphene is used in some implementations.
  • the tube-shaped carbon nanotubes have diameters in the nanometer scale, such as, for example, between about 0.2 and about 20 nm, preferably between about 0.5 and about 10 nm, and more preferably still between about 1 and about 5 nm.
  • These can be single walled carbon nanotubes (SWCNT), multi walled carbon nanotubes (MWCNT) (e.g., a collection of 2 or more nested tubes of continuously increasing diameters, or mixtures of these).
  • the diameters of MWCNT can be larger than the SWCNT, such as between about 1 and about 100 nm (e.g., between about 1 and about 50 nm, between about 10 and 20 nm, between 5 and 15 nm, between about 30 and 50 nm).
  • different isomers of carbon nanotube can be made, for example designated as armchair configuration, chiral configuration, and zigzag configuration.
  • the carbon nanotubes and reduced graphene oxide can include intercalated materials, such as ions and molecules.
  • the carbon nanotubes can be functionalized for example by oxidation to form carboxylic acid groups on the surface, providing CNTs.
  • the carbon nanotubes and rGO can be further modified through condensation reactions with the carboxylic acid groups present on the CNTs or rGO (e.g., with alcohols and amines), electrostatic interactions with the carboxylic acid groups (e.g., calcium mediated coupling, or quaternary amines, protonated amine-carboxylate interaction, through cationic polymers or surfactants) or hydrogen bonding through the carboxylic acid groups (e.g., with fatty acids, and other hydrogen bonding molecules).
  • the carboxylic acid groups present on the CNTs or rGO e.g., with alcohols and amines
  • electrostatic interactions with the carboxylic acid groups e.g., calcium mediated coupling, or quaternary amines, protonated amine-carboxylate interaction, through cationic polymers or surfactants
  • hydrogen bonding through the carboxylic acid groups e.g., with fatty acids, and other hydrogen bonding molecules.
  • the functionalization can be partial (e.g., wherein less than 90%, less than 80%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, more than 10%, more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, of the available carboxylic acid groups are functionalized) or complete, such as functionalizing substantially all the carboxylic acids (e.g., more than 90%, more than 95%, more than 99% of available carboxylic acid groups).
  • the functionalization can be with a redox active compound or fragment (e.g., a metallocene, a viologen), antibody, a DNA strand, an RNA strand, a peptide, an antibody, an enzyme, a molecular receptor, a fragment of one of these or combination of these.
  • a redox active compound or fragment e.g., a metallocene, a viologen
  • the allotropes of carbon having hexagonal lattices of carbon atoms can confer electroactivity (e.g., conductivity) to the compositions and structures herein described.
  • Other conductive elements such as pure graphene, fullerenes, conductive and semi- conductive particles, rods, nano-rods, micro-rods, fibers, nano-fibers, micro-fibers, particles, nanoparticles and micro-particles (e.g., Gold), and conductive polymers (e.g., polypyrrole, polythiophene, polyaniline) can also be used to replace the CNTs and rGO or blended/combined with CNTs to modulate (e.g., improve) the conductivity, improve the stability and/or improve the stability of the coatings.
  • the coatings conduct in a direction perpendicular to the surface of an electrode, equivalent herein to “vertically”, to a greater degree than in directions parallel or tangential to the surface of the electrode, equivalent herein to “laterally”. In Cartesian coordinates this can correspond to higher conduction in the z direction (perpendicular to the electrode surface) than in the x and y directions (e.g., combinations of x and y pointing vectors).
  • the conductivity in the vertical direction is at least two times (e.g. at least 3 times, 4 times, 5 times, 10 times, 100 times, 1000 times) higher than that in the lateral direction.
  • the mixture of particulate material and proteinaceous material can be coated by any method.
  • these methods include spraying, spin coating, dip coating, inkjet printing, vapor deposition, 3-D printing, painting, and/or drop casting.
  • the methods include continuous or semi-continuous methods.
  • the mixture can be spin or dip coated on a wafer having a plurality of electronic transducers patterned thereupon.
  • Each spin or dip coating step can be part of a multi-step process in a fab or foundry (e.g. a semiconductor fabrication plant) involving a continuous train of wafers. Such a process can be considered as semi-continuous.
  • coating can be using a reel to reel (or roll to roll) method.
  • Reel to reel processing is a fabrication method used in manufacturing that embeds, coats, prints, or sprays the mixture onto a flexible rolled substrate material, such as a web or sheet, as that material is fed continuously from one roller on to another roller.
  • Reel to reel is a continuous process.
  • the particulate material and proteinaceous material is coated immediately before it is used. For example, an electrode or other device is coated and immediately and used in an assay within an hour of preparing the coating.
  • the particulate material and proteinaceous material forms a very robust coating and can be used at least a day, at least two days, at least a week, at least two weeks, at least a month, at least three months, at least six months, at least a year, at least two years after preparation, where the electrode or device signal retains at least about 90% of its original signal.
  • the electrode or device that is coated with the particulate material and proteinaceous material is stored between about 0 °C and 50 °C before being used, for example between about 0 °C and 50 °C, between about 0 °C and 40 °C, between about 10 °C and 50 °C, between about 20 °C and 40 °C, between about 20 °C and 30 °C.
  • an electrode or device with the particulate material and proteinaceous material coating can be used in an assay such as a precipitated sacrificial redox active molecule on the electrode surface (e.g., containing TMB), where the signal can be detected at least a day, at least two days, at least a week, at least two weeks, at least a month, at least three months, at least six months, at least a year, at least two years after the precipitation of the redox active material.
  • an assay such as a precipitated sacrificial redox active molecule on the electrode surface (e.g., containing TMB), where the signal can be detected at least a day, at least two days, at least a week, at least two weeks, at least a month, at least three months, at least six months, at least a year, at least two years after the precipitation of the redox active material.
  • the electrode or device that is coated with the particulate material and proteinaceous material, and includes a sacrificial redox active molecule is stored between about 0 °C and 50 °C before the redox active molecule is detected, for example between about 0 °C and 50 °C, between about 0 °C and 40 °C, between about 10 °C and 50 °C, between about 20 °C and 40 °C, between about 20 °C and 30 °C.
  • the methods can be used to make multilayer materials, alternating between a layer of the coating of proteinaceous material and a substrate material. For example; a first mixture comprising a first particulate material and a first proteinaceous material is coated on a first substrate, providing a first proteinaceous layer on the first substrate; a second mixture comprising a second particulate material and a second proteinaceous material is coated on a second substrate, providing a second proteinaceous layer on the second substrate; a third mixture comprising a third particulate material and a third proteinaceous material is coated on a third substrate, providing a third proteinaceous layer on the third substrate; etc.
  • the layered material can start with a substrate material, with the final layer being a substrate material, or with the final layer being a substrate material. In some implementations, the layered material can start with a substrate material, with the final layer being a substrate material, or with the final layer being a substrate material.
  • Each of the compositions of particulate materials and proteinaceous materials for the coatings e.g. first, second, third
  • Each of the substrate materials for the coatings e.g. first, second, third
  • Such multilayer films can be prepared, for example, by standard semiconductor manufacturing methods.
  • substrates such as metals can be layered onto the proteinaceous coatings by sputtering, vapor phase deposition, electrodeposition etc.
  • the mixtures of particulate material and proteinaceous material are sprayed or spin coated on the substrate layers.
  • patterning, creation of vias (e.g. conductive vias such as copper or aluminum), lines (e.g., conductive lines such as copper or aluminum) by combinations of deposition, etching, masking and planarization can also be implemented.
  • the pattering includes through holes providing access to the internal layers in the internal structure such as can be accessed by analytes.
  • the anti-fouling coatings described herein can be applied to surfaces of microfluidic devices. These devices can include channels through which fluids can flow and chambers for holding the fluids. Electronic transducers can be included and the anti-fouling coatings can be used to protect these and other parts of the device.
  • the coating is a cross-linked and porous gel, and a channel or chamber is completely or mostly filled in. Analyte can flow through the pores and be detected, for example, by binding to a capture molecule such as an antibody, DNA strand, or aptamer.
  • the coatings can be patterned to provide hydrophilic/hydrophobic areas for movement or holding of fluids.
  • the coatings can be patterned as a conductive wire or a dielectric/insulating surface.
  • the coatings can be used in nano-gap and micro-gap devices.
  • these devices include nano-gap electrodes, nanostructured-based electrical biosensors, and nano-gap dielectric biosensor for label free DNA hybridization detection.
  • the coatings can be applied, for example, to the gap between electrodes in the device and thereby protect the surfaces of the gap from fouling.
  • the coating is a cross-linked and porous gel, and the gap is completely or mostly filled in. Analyte can flow through the pores and be detected, for example, by binding to a capture molecule such as an antibody, DNA strand, or aptamer.
  • the coatings are used for medical devices.
  • the tips of needles can be coated.
  • the medical device is an implantable device.
  • the coatings can be used in lateral flow assay devices.
  • the coatings can be used for wearable devices, such as transdermal patches, devices to detect biological agents or toxins.
  • Embodiment 1 A method for making a coating on a surface of a substrate, the method comprising: applying a mixture to a surface of a substrate while maintaining the substrate at an elevated temperature, wherein the mixture comprises a particulate material and a proteinaceous material.
  • Embodiment 2 The method of Embodiment 1, wherein the mixture further comprises a cross-linking agent.
  • Embodiment 3 The method of Embodiment 1 or 2, wherein the proteinaceous material includes a cross linking agent attached to or as part of the proteinaceous material’s structure.
  • Embodiment 4 The method of any one of Embodiments 1-3, wherein the elevated temperature is maintained for at least 10 seconds and less than two minutes.
  • Embodiment 5 The method of any one of Embodiments 1 -4, wherein the elevated temperature is at least 50 °C.
  • Embodiment 6 The method of any one of Embodiments 1-5, wherein the method further comprises denaturing the proteinaceous material.
  • Embodiment 7 The method of Embodiment 6, wherein said denaturing the proteinaceous material is prior to mixing the proteinaceous material with the particulate material and/or after applying the mixture to the substrate.
  • Embodiment 8 The method of any one of Embodiments 1-7, wherein the substrate is a particle, a nano-particle, a micro-particle, a nano-fiber, a micro-fiber, a flake, a chip, a crystal, a porous substrate, a wafer, a wire, a nano-wire, a micro-wire, a channel, a nano-channel, a microchannel, a rod, a nano-rod, a micro-rod, a foil, a sheet, a web, or combination of these forms.
  • Embodiment 9 The method of any one of Embodiments 1-8, wherein the substrate comprise a material selected from the group consisting of metals, polymers, carbon based materials, ceramics, glass and any combinations thereof.
  • Embodiment 10 The method of any one of Embodiments 1-9, wherein the substrate includes gold.
  • Embodiment 11 The method of any one of Embodiments 1-10, wherein the substrate includes graphite, diamond, glassy carbon, or carbon nano-tubes.
  • Embodiment 12 The method of one of Embodiments 1-11, wherein the substrate includes an organic polymer.
  • Embodiment 13 The method of any one of Embodiments 1-12, wherein the particulate material is a rod, fiber, a particle, a flake or combinations of these.
  • Embodiment 14 The method of any one of Embodiments 1-13, wherein the particulate material is a dielectric.
  • Embodiment 15 The method of any one of Embodiments 1-14, wherein the particulate material is a conductor or semi-conductor.
  • Embodiment 16 The method of any one of Embodiments 1-15, wherein the particulate material comprises an allotrope of carbon atoms arranged in a hexagonal lattice.
  • Embodiment 17 The method of any one of Embodiments 1-16, further comprising a step of pre-treating the substrate prior to applying the mixture.
  • Embodiment 18 The method of any one Embodiments 1-17, wherein applying the mixture comprises spraying, spin coating, dip coating, inkjet printing, vapor deposition, 3-D printing, painting, and/or drop casting.
  • Embodiment 19 The method of any one ofEmbodiments 1-18, wherein the method is a continuous process or semi-continuous process (e.g. reel to reel, pattern deposition on a wafer).
  • Embodiment 20 The method according to any one of Embodiments 1-19, further comprises denaturing the proteinaceous material and subsequently adding a temperature sensitive material to the mixture prior to coating the substrate.
  • Embodiment 21 The method according to any one ofEmbodiments 1-20, wherein the substrate surface defines a channel or chamber, such as a channel or chamber in a microfluidic device.
  • Embodiment 22 The method according to any one ofEmbodiments 1-21, wherein the substrate is a micro/nano gap devices where the coating can enable higher sensitivity and the coating can either be used to coat the surfaces of a gap in the miro/nano gap device, or the coating is applied for surface modification to enable linking of specific probes and antifouling properties.
  • Embodiment 23 The method of any one ofEmbodiments 1-22, further comprising applying a layer of a second substrate on the coating of proteinaceous material and optionally coating a second mixture comprising a second mixture and second proteinaceous material on the second substrate, providing a layered material having alternating layers of substrate and proteinaceous/particulate material.
  • Embodiment 24 A substrate comprising a coating on a surface thereof, wherein said coating is applied using a method of any one ofEmbodiments 1-23.
  • Embodiment 25 The substrate of Embodiment 24, wherein the substrate is an electrode, a capacitor, a bio-Field Effect transistor (bio-FET), transistors, and optical devices.
  • bio-FET bio-Field Effect transistor
  • Embodiment 26 A capacitor comprising a dielectric material dispersed in a denatured and cross-linked proteinaceous material, and covering a conductive substrate.
  • Embodiment 27 A bio-FET comprising a composition including a particulate material dispersed in a denatured proteinaceous material and coating at least a portion of a transistor.
  • Embodiment 28 The bio-FET according to Embodiment 27, wherein the compositing is coated on a gate of the bio-FET.
  • the unprecedented selectivity of the coating allowed the development of a multiplexed platform that can be used to triage patients suffering from Myocardial Infarction and Traumatic Brain Injury using only 15 pL of the sample.
  • a single-digit pg/mL sensitivity was obtained with all the markers tested in unprocessed human plasma samples and whole blood, which is at least 50 times more sensitive than traditional ELISA methods and accomplished in one-eighth of the time.
  • the signal adsorbed on the coating could be conserved and measured over one week.
  • the platform was validated with 22 clinical samples that demonstrated excellent correlation with obtained reported values.
  • a previously reported anti-fouling coating method based on gold nanowires and graphene addresses some of these limitations, but can take 24 hours to coat.
  • the stability of coating at room temperature was assessed over months. Furthermore, the stability of signal of adsorbed TMB was recorded over a week, opening the possibility of shipping without compromising biomarker stability.
  • TBI Traumatic Brain Injury
  • MI myocardial infarction
  • TBI is the worldwide leading cause of mortality and morbidity in young adults, and in the U.S., roughly 1.7 million suffer from TBI each year. At least 5.3 million live with severe disabilities related to TBI. Cardiovascular consequences resulting from moderate and severe TBI has long been recognized and are associated with an increase in-hospital mortality, so timely recognition and management of these patients is required.
  • TBI leads to heterogeneous pathology that affects multiple cells and tissue types, necessitating simultaneous measurement of multiple biomarkers similar to AMI, which require multiple biomarkers in clinical practice.
  • Multiplexed immunoassays are required for patient stratification and monitoring of multifactorial diseases like MI and TBI.
  • relatively scarce protein multiplexing immunoassays have been validated for POC settings.
  • the direct multiplexed determination of biomarkers in complex biological media remains a significant challenge due to biofouling and the lack of high-quality antibody pair resulting in cross-reactivity and preventing the scale up.
  • the herein described ultrafast coating method addressed these challenges.
  • the method has exceptional anti-fouling properties and limitless manufacturing capabilities in a cost-effective way, for a multiplexed platform to triage patients suffering with MI from TBI in 37 min from 15 uL of unprocessed human plasma samples.
  • the ultrafast coating process improves on a previous overnight treatment.
  • the process includes heat treatment of the coating solution directly onto the biosensor surface, which leads to rapid binding of the coating solution.
  • the physical and/or chemical structure leading to antifouling activity or maintaining physio-chemical properties (conductivity) is comparable to the overnight processes.
  • the rapid coating method can be used for mass manufacturing for Biosensors for instance in reel to reel manufacturing of sensors and can be used, for single or multiplexed assays.
  • the coating solution can also be applied on relatively inert materials including but not limited to plastics and polymers (Poly (methyl methacrylate), polyethylene, polystyrene) after surface modifications/treatment like plasma treatment or UV cross linking to develop anti-biofouling biosensors.
  • plastics and polymers Poly (methyl methacrylate), polyethylene, polystyrene) after surface modifications/treatment like plasma treatment or UV cross linking to develop anti-biofouling biosensors.
  • a mixture was prepared by adding 2 mg of pentaamine functionalized graphene oxide to 5 mg/mL BSA in PBS.
  • BSA pentaamine functionalized graphene oxide
  • a recombinant BSA and other proteins can be used.
  • the mixture was sonicated for 1 hour with 1 second on/off pulses and then heated for 5 minutes at 105.5 C. Once cooled to room temperature, the mixture was centrifuged at 16.1 rfc for 15 minutes and the supernatant was collected and used as the coating solution.
  • Gold on glass chips were cleaned by sonicating in acetone for 15 minutes, rinsing with IPA, and sonicating in IPA for 15 minutes. The chips were then dried with pressurized nitrogen and plasma treated. The chips were separated into two groups: “overnight” coating and “fast” 1 min coating. The overnight chips were coated with 69 pL of a mixture of 1 :69 glutaraldehyde in the graphene oxide coating and incubated overnight in the dark at room temperature. The fast coating chips were first heated to 90 °C on a hot plate. A solution of 69 pL of a mixture of 2:69 glutaraldehyde in the graphene oxide containing coating solution was added to the chips. The chips were removed from heat after 1 minute.
  • cyclic voltammetry was performed on the chips from -0.5 to 0.5 V at the scan rate of 0.2 V/s and the height of the oxidation peak current were recorded.
  • the length of incubation on the hot plate was optimized by testing different times from 1 minute up to 10 minutes. However, no incubation period exceeding 1 minute yielded viable chips. This is shown by the CV plots where at 1 minute strong anodic/cathodic peaks are seen (about ⁇ 7.8 pA). At 3, 5 and 10 minutes no signal is observed, as shown by the overlapping flat line.
  • the concentrations of BSA in PBS was determined by varying the concentration from 0.5 to 10 mg/mL, as illustrated by FIG. 2.
  • the legend represents the ratio of glutaraldehyde to graphene oxide-BSA solution.
  • the best anti-fouling concentration was 5 mg/mL, which shows the smallest difference between the overnight coating and ethanolamine quenched samples, while having a high conductivity.
  • the glutaraldehyde concentration in graphene oxide - BSA mixture was varied from 1:70 (pL:pL) to 6:70. Three ratios are illustrated in the bar plot shown in FIG. 3. The recorded currents were all about equal and within the error of the measurements between the 1 hr treatments and overnight treatments. The 1:70 ratios did not yield any signal for. The best ratio was selected as 2:70, since there was no detectable difference across conditions and the least amount of glutaraldehyde was used.
  • the pentaamine-functionalized graphene oxide was varied in concentration from 0.5 to 4 mg/mL.
  • FIG. 4 shows a plot of the results for three concentrations. At the dilute end of the spectrum, little to no signal was displayed. At 1 mg/mL a good signal was seen at 1 hour, which decreased overnight. At 2 mg/mL and greater the peak height reached a maximum, where the signal degradation stabilized. For example, compare 2 mg/mL and 4 mg/mL which show similar performance. Thus, the concentration of 2 mg/mL was chosen as the best concentration for optimal signal and lowest amount of graphene oxide.
  • the chips were allowed to cool down to room temperature and then washed with PBS for 10 minutes under in a shaker at 400 rpm. The overnight chips were similarly washed after the overnight incubation.
  • FIG. 5 shows the plotted results.
  • the 1 -minute deposition method demonstrated comparably anti-fouling capabilities to the overnight method.
  • the decrease in signal is negligible after 1 hour of BSA and about a 20-25% decrease after the overnight BSA step. This exhibits the ability of the fast coating to perform at the same level as the overnight protocol.
  • each group of chips were incubated in EDC/NHS (77 mg/23 mg) in MES buffer (1 mL) for 30 minutes. Chips were then rinsed with water, air dried, and the electrodes were spotted with 1 mg/mL NT-proBNP capture antibody in PBS. One electrode per chip was spotted with 5 mg/mL BSA in PBS as a negative control. Once spotted, chips were stored overnight in 4 °C.
  • the detection antibody (15 minutes), poly-streptavidin-HRP (5 minutes), and TMB One Component (1 min) were added. Washing steps with PBST were completed in between each component. To measure the signal of the assay, cyclic voltammetry was performed on the chips from -0.5 to 0.5 V at the scan rate of 1 V/s and the height of the oxidation peak current were recorded.
  • FIG. 6 illustrates the comparison of the fast and overnight protocol for deposition of an anti-fouling coating. This demonstrates that a rapid deposition coating performs equally well to the overnight protocol. Electrodes spotted with BSA had no signal for both methods, nor did electrodes that were exposed to 0 ng/mL NT-proBNP in plasma. In the absence of analyte, both methods performed appropriately by displaying a lack of signal and no non-specific binding.
  • the method developed is a route to implementation of fast manufacturing such as reel to reel method for mass production of sensors. Furthermore, the methods enable deposition of nano-composite layer using techniques such as spray painting over a range of surfaces including metals and polymers.
  • FIG. 7 A 3D schematic of a gold electrode with antifouling nanocomposite is illustrated by FIG. 7.
  • the nanocomposite coating recipe was developed using on-chip heating to facilitate the coating deposition. Clean sensors comprising of gold electrodes were heated at 85 °C with nanocomposite material for a period ranging from 30 s to 5 min, followed by washing in PBS immediately or after cooling down for 10 min.
  • FIG. 8 is a plot showing electrochemical characterization of the coating for the development of the optimum heating time where sensors are washed just after heating or after cooling down for 10 min. Bar shows the current density of the sensors.
  • FIG. 9A and 9B are CV plots showing typical oxidation and reduction peaks of an equimolar solution of 5 mM ferri -/ferrocyanide of sensor coated with nanocomposite at 85 °C for different periods followed by immediate dipping in water at room temperature (9A) and cooling to room temperature before dipping (9B.
  • the sharp decrease post 90 s could be attributed to over crosslinking of the nanocomposite on the sensor surface, leading to passivation of the surface.
  • the CV obtained using the coating shows a near reversible process with a peak-to-peak distance of 143 mV.
  • the sensors coated for 30, 45, and 60s were functionalized with antibodies, and a simple EC-Assay of cTnITC was performed in parallel. Although there was no significant difference in current density at higher concentrations of cTnITC (1 and 0.1 ng/mL) at lower concentration (0.05 ng/mL), EC-Biosensor coated for 45 and 60 s gave higher current compared to other EC-Biosensors.
  • FIG. 10 is a plot showing optimization of coating time for sensors.
  • Bar graph shows the assay of cTnITC with sensors coated with antifouling coating for 30s (black dot), 45s (blue dot), and 60s (red dot).
  • coating for 45 s also provides more room for coating time variation; thus, 45 s of coating time was used for further studies and characterization.
  • rGOx reduced graphene nanoparticles
  • functional groups like amines augments the interaction with the polymer matrices and distribution of the nanoflakes by altering its solubility and agglomeration and also enhance the physical, mechanical, thermal, and electrical stability through the covalent linking by glutaraldehyde pyridine polymers.
  • prGOx pentaamine-functionalized rGOx
  • FIG. 11 is a plot showing optimization of rGOx. Bars are the current density of amine-functionalized GOx (black) and pentaamine functionalized GOx (grey)..
  • FIG. 12 shows that with the increase in the concentration of BSA from 0.5 to 5 mg/mL (with all ratios of GA), the current density of the sensor increases. However, further increase (to 10 mg/mL) leads to a decrease in current density, although peak-to-peak distance remains consistent. The insulation effect at higher concentration could be due to increased cross-linking as GA can react with proteins through various mechanisms depending upon different forms it can be present in solution, which is primarily developed through empirical observation. 5 mg/mL of BSA with 2:70 ratio of GA: BSA was used for further characterization as it maintained the highest conductance.
  • FIG. 13 A is a plot showing optimization of concentration of prGOx. Bars are the current density of various nanocomposite with different concentrations of prGOx; fresh coating (black) and after 1-h exposure to 1% BSA (grey).
  • FIG. 13B shows a typical CV showing oxidation and reduction peaks of an equimolar solution of 5 mM ferri-/ferrocyanide of various nanocomposite-coated electrodes.
  • the coated gold electrodes maintained a similar current density (102%) compared to the bare gold electrode, while BSA/GA coatings resulted in a reduction of current density (36.3% of the fresh coating).
  • BSA/GO coating maintained higher current density (84.5%) than BSA coating (32.6%) which may be due to nanoparticle-mediated electron transfer in BSA/GO.
  • Sensors coated with various coatings were challenged by exposing to 1% BSA for 24h. As expected, bare gold and different coatings (BSA, BSA/GA) exhibited reduced electrochemical performance except for the BSA/GO, which maintained a relatively high current density.
  • FIG. 14 is a plot showing electrochemical characterization of various electrode coatings. Bars are the mean current density of various nanocomposite-coated electrodes fresh (black) and after 1-d exposure to 1% BSA (grey). Even after 1-d of incubation in 1% BSA, the coating with BSA/prGOx/GA maintained a very high current density of 95.1% and low AEp of 185 mV. In addition, for assessing the mass transport of potassium ferri -/ferrocyanide with BSA/prGOx/GA coated electrodes, CV at different scan rates was evaluated.
  • FIG. 15 shows CVs of bare gold- (left) and coated gold electrodes (right) of an equimolar solution of 5 mM ferri- /ferrocyanide at different scan rates (0.01-1.0 V/s).
  • FIG. 16 shows a plot of extracted oxidation/reduction peak current (ip) mean values for gold electrode (black circles) and electrode with the coating (white circle) from the CV shown in FIG. 15 plotted versus the square root of the scan rate.
  • the anti-fouling properties of a given strategy or nanocomposite are evaluated only towards one analyte/interferant, it limits the general assessment of how an anti-fouling strategy may work for the clinical diagnostics of various biomarkers. Therefore, the antifouling activity with complex biological fluids like plasma along with 1% BSA was evaluated.
  • the rapidly coated nanocomposite showed excellent anti-fouling properties as shown by the high current density of the nanocomposite coated sensor both with 1% BSA (100.1% after one week and 95.5% after nine weeks) and plasma sample (107.2% after one week and 88.0% after nine weeks) as compared to the fresh bare gold electrode that showed a rapid decrease in current density to zero after one day in plasma.
  • FIG. 17 shows a plotted comparison of antifouling activity with mean value of current density recorded at bare gold electrodes and Gold electrodes with antifouling coating stored for 9 weeks at 4 °C in 1% BSA and unprocessed human plasma. Red circles in FIG. 17 denote the final mean value of peak-to-peak distances.
  • Statistical analysis in c, d, and e was performed using unpaired t-tests: *P ⁇ 0.05, **P ⁇ 0.01.
  • the coated sensors were also challenged with whole blood, saliva, and urine for 1 hour without any significant reduction in current density.
  • FIG. 18A and 18B are plots characterizing the antifouling nanocomposite coating.
  • Bar graph (18A) shows current density of fresh sensors (black bar) and sensors after 1 hour in varying biofluids: whole blood, saliva, and urine (grey bar).
  • UV absorption spectra (18B) of BSA when mixed with/without GA and/or GOx. a.u., arbitrary units. Error bars represent the s.d. of the mean, n 3. Significance was determined by unpaired /-test ( ns P > 0.05; *P ⁇ 0.05; **P ⁇ 0.01; all two tailed.
  • FIG. 19A-19E are scanning electron micrograph of the bare Gold (19A, 19D), Gold/BSA/GOx (19B), and Gold/BSA/GOx/GA (anti-fouling coating) (19C, 19E).
  • FIG. 20A-20B illustrate the surface roughness characterized using Atomic Force Microscopy (AFM).
  • FIG. 20A shows a 3D image of roughness sfor the bare gold electrode
  • FIG. 20B shows a 3D image of coated gold electrode.
  • FIG. 20C-20H show TEM images of bare gold (20C, 20F), coated gold electrode with top Iridium layer (20D, 20G), and without top Iridium layer (20E, 20H) for better contrast.
  • FIG. 21 A-21B show AFM 2D (21A) and 3D (21B) survey images of bare gold electrode, (5mm x 1.2mm x 50nm), the blue square marks the approximate analysis location for the 1mm x 1mm images.
  • FIG. 21C-21D show AFM 2D (21C) and 3D (21D) survey images of gold electrode with antifouling coating (5mm x 1.2mm x 50nm), the blue square marks the approximate analysis location for the 1mm x 1mm images.
  • Table 1 Roughness Results for AFM of bare gold and gold with coating.
  • FIG. 22 shows an XPS spectra for gold electrode coated with antifouling coating.
  • Table 2 shows concentration of elements as determined by XPS.
  • Table 2 Atomic Concentrations (in atomic %) Normalized to 100% of the elements detected. XPS does not detect H or He.
  • the antifouling coating also increases the sensor's hydrophilicity compared to Gold/BSA and Gold/BSA/GOx (FIG. 23K-23L, 25A-25F), which facilities the binding of capture antibody.
  • FIG. 23 A-23L depict the characterization of the antifouling nanocomposite coating.
  • XPS X-ray Photoelectron Spectroscopy
  • Ions characteristic of BSA including CH4N+, CH3N2+, C2H6N+, C4H5O+, C 4 H 8 N+, C 3 H 8 NO+, C5H12N+, C3H8NO+, C5H12N+, C4H10N3+, C 8 HION+, and C9H8N+ were observed (FIG. 23E and 23F). Additional species observed include hydrocarbon species, aromatic species, and small oxygen-containing organic ions, including C-, CH-, C2-, C2H-, C3-, C4-, C4H-, CsH-, C7H-, CN-, and CNO- as also seen in the literature indicating the presence of graphene oxide and BSA (FIG. 23G and 23H).
  • Table 3 Carbon Chemical States (in % of Total C) Values in this table are percentages of the total atomic concentration of the corresponding element shown in Table 2.
  • FIG. 24A-24G show schematics and calibration curves for MI and TBI biomarkers using EC-biosensors and 96 well plate.
  • FIG. 24A shows a schematic for the preparation and assay steps for the EC-Biosensor.
  • FIG. 24B-24G are calibration curves for different biomarkers.
  • the left y-axis shows current density for different concentrations of biomarkers run on EC-Biosensors (red circle) using unprocessed human plasma while the right y-axis shows mean absorbance (a.u) for different concentration of biomarkers run in 96 well plate using plasma (black triangle) and 1% BSA in PBS (blue triangle).
  • 4PL 4-Parameter Logistic
  • FIG. 25A-25F are images of a drop on a chip for contact angle measurements.
  • FIG. 25A is an uncleaned chip with protective organic layer.
  • FIG. 25B is a chip cleaned with acetone and Isopropyl alcohol.
  • FIG. 25C is a plasma treated chip.
  • FIG. 25D is a plasma-treated chips with BSA coating.
  • FIG. 25E is a plasma-treated chip with BSA and GOx coating.
  • FIG. 25F is a plasma- treated chips with antifouling nanocomposite coating.
  • the capture and detection antibody for the assay was optimized to meet the clinical cut-off range of each biomarker, while poly streptavidin HRP (5ug/mL) and TMB timing (2 min) was optimized based on troponin I considering the high sensitivity required for troponin I assay (FIG. 27A-27G). It is noted that the EC-Biosensor showed ultra-high selectivity with no background signal for commonly found interfering molecules in biological samples like uric acid, dopamine, and tryptophan, as shown by FIG. 27H-28J).
  • FIG. 26A-26C illustrates optimization and two-step assay for different biomarkers.
  • FIG. 26A shows optimization of detection antibody for the assay of cTnl.
  • Left y-axis show current density for 1 ng/mL (blue) and 0 ng/mL (green) of cTnITC while right y-axis shows signal to noise ratio at different concentration of anti-cTnl detection antibody.
  • FIG, 26B is a calibration curve of cTnl run on the EC Biosensor with antifouling coating using two-step assay and optimized detection antibody concentration.
  • FIG. 27A-27G illustrates assay development and optimization for single step assay for different biomarkers.
  • FIG. 27A shows optimization of cTnl capture antibody. Bar graph shows the mean current density for different concentration of capture antibody (50, 100, 500, and 1000 pg/mL) to perform assay of cTnl at 3 different concentrations (10, 0.1, and 0 ng/mL).
  • FIG. 27B shows optimization of cTnl detection antibody. Bar graph shows the mean current density for different concentration of detection antibody (1, 2, 3, 5, and 8 pg/mL) to perform assay of cTnl at 3 different concentrations (10, 0.1, and 0 ng/mL).
  • FIG. 27C shows optimization of HRP- Streptavidin.
  • Bar graph shows the mean current density for different concentration of HRP- Streptavidin (1, 2, 3, 5, and 8 pg/mL) to perform assay of cTnl at 3 different concentrations (10, 0.1, and 0 ng/mL).
  • FIG. 27D shows optimization of TMB incubation time.
  • Bar graph shows the mean current density for different incubation time for TMB (1 and 2 min) to perform assay of cTnl at different concentrations (10, 1, 0.5, 0.1, 0.05, 0.01, and 0 ng/mL).
  • FIG. 27E shows optimization of BNP detection antibody.
  • Bar graph shows the mean current density for different concentration of detection antibody (3, 6, 9, 12, and 15 pg/mL) to perform assay of BNP at 3 different concentrations (10, 0.1, and 0 ng/mL).
  • FIG. 27F shows optimization of NT-proBNP detection antibody.
  • Bar graph shows the mean current density for different concentration of detection antibody (1, 3, 6, and 9 pg/mL) to perform assay of NT-proBNP at 3 different concentrations (10, 0.1, and 0 ng/mL).
  • FIG. 27G shows optimization of cTnITC detection antibody.
  • FIG. 27H-27J illustrate cross-reactivity test of the EC Biosensor. CV oxidation and reduction peaks of uric acid (27H), Dopamine (271), and Tryptophan (27J) at 3 different concentrations (at, higher, and lower than physiological level) along with cTnITC at 0.1 ng/mL [00182] FIG.
  • FIG. 28A-28F shows characterization and stability of antifouling nanocomposite and precipitated TMB.
  • FIG. 28A shows an assay of NT-proBNP comparing the mean current density for different concentrations of NT-proBNP done on EC-Biosensor with rapid coating (blue) and 24h coating (red).
  • FIG. 28C shows stability of precipitated TMB for detection of cTnITC.
  • FIG. 28E shows stability of coating solution stored at 4 degrees.
  • FIG. 28F shows stability of coating solution stored at room temperature.
  • a, b, c significance was determined by multiple/unpaired /-test ( ns P > 0.05; *P ⁇ 0.05; **P ⁇ 0.01 ***P ⁇ 0.001; ****P ⁇ 0.0001; all two-tailed.
  • Two-way ANOVA was used to observe a significant source of variation, ns P > 0.05.
  • FIG. 29A-29E illustrates the specificity and Multiplexed detection for MI and TBI Biomarkers using EC-Biosensors.
  • FIG. 29A shows a schematic for multiplexed detection on the EC-Biosensor showing detection of four biomarkers in a single EC-Biosensor.
  • FIG. 29B shows Specificity and cross-reactivity of BNP antigen against different capture antibodies (anti-cTnITC, anti -NT -proBNP, anti-GFAP, and anti-S-lOOb) and detection antibodies (anti-cTnITC, anti-NT- proBNP, anti-GFAP, and anti-S-lOOb) along with specific detection with anti -BNP capture and detection antibody at different concentrations of BNP done in 96 well plate.
  • FIG. 29C shows a calibration curve for multiplex detection of cTnITC on the EC-Biosensor with four different capture antibodies on each electrode (anti-cTnITC, anti-S-lOOb, anti-GFAP, and anti-NT-proBNP).
  • FIG. 29D shows a calibration curve for multiplex detection of increasing concentrations of cTnITC (left y-axis) and decreasing concentrations of GFAP (right y-axis) on the EC-Biosensor with four different capture antibodies on each electrode.
  • FIG. 29C shows a calibration curve for multiplex detection of cTnITC on the EC-Biosensor with four different capture antibodies on each electrode (anti-cTnITC, anti-S-lOOb, anti-GFAP, and anti-NT-proBNP).
  • FIG. 29D shows a calibration curve for multiplex detection of increasing concentrations of cTnITC (left y-axis) and decreasing concentrations of GFAP (right y-axis) on the EC
  • 29E shows a calibration curve for multiplex detection of increasing concentrations of cTnITC and S-lOOb (left y-axis) and decreasing concentrations of GFAP and NT-proBNP (right y-axis) on the EC-Biosensor with four different capture antibodies on each electrode.
  • FIG. 30A-30H illustrates microfluidic integration and clinical validation of the assay.
  • FIG. 30A is a picture of a microfluidic device where six EC-Biosensors can be placed to run the assay in parallel.
  • FIG. 3 OB is a 3D schematic of the microfluidic channels and their interface with the EC-Biosensor.
  • FIG. 30C shows a calibration curve for the assay of cTnITC performed on the microfluidic platform with reduced assay time using spiked plasma samples.
  • FIG. 30D shows a calibration curve for the assay of GFAP performed on the microfluidic platform using spiked plasma samples.
  • Bland- Altman plot for validation of EC Biosensor using clinical sample for cTnITC is shown by FIG. 3 OF and for GFAP is shown by FIG. 3 OH.
  • Troponins released into the bloodstream are mainly non-covalent ternary complex, cTnl-T-C (ITC complex), and binary complex cTnl-C (IC complex) with some free form of cTnl to some extent.
  • ITC complex non-covalent ternary complex
  • IC complex binary complex cTnl-C
  • FIG. 24E shows the calibration curve of cTnITC with LOD of 3, 24, and 17 pg/mL for EC-Biosensor, 96 well plasma, and buffer, respectively. LOD obtained is better than the 99th percentile cutoff value (28 pg/mL) in a healthy population used for cardiac troponin assay.
  • FIG. 31A-31F illustrates an assay of different biomarkers on EC-Biosensor. TMB oxidation and reduction peaks obtained with a CV on EC Biosensors with antifouling coating for detection of different concentrations of biomarkers of Myocardial infarction and Traumatic Brain Injury.
  • FIG. 31A shows BNP
  • FIG. 3 IB shows NT-proBNP
  • FIG. 31C shows cTnl
  • FIG. 3 ID shows cTnITC
  • FIG. 3 IE shows GFAP
  • FIG. 3 IF shows SI 00b.
  • Table 4 Sensitivity and Kd values for detection of biomarkers of MI and TBI in EC- Biosensor with antifouling coating and 96 well assay.
  • BNP which degrade in circulation rapidly
  • NT-proBNP show variable levels in circulation according to the clinical condition and timing of measurement for MI, which necessitates a rapid and sensitive POC device.
  • a sensitivity of 26 pg/mL was obtained with EC-Biosensor, which was almost 1000X better than 96 well plate (2.7 ng/mL) (FIG. 24C).
  • FIG. 24D shows the assay of NT-proBNP with LOD of 4 pg/mL, 65 pg/mL, & 54 pg/mL for spiked plasma samples in EC-Biosensor, 96 well plasma, and buffer, respectively.
  • the sensitivity for EC-Biosensor was far better than the clinical cut-off values for BNP (35 pg/mL) and NT-proBNP (125 pg/mL) that have high negative predictive values (0.94-0.98) and can be used for ruling-out HF according to ESC guidelines.
  • LOD for S 100b was found to be 1 pg/mL in EC-Biosensor while 96 well assay for S 100b in spiked plasma and buffer had LOD of 957 and 432 pg/mL, respectively.
  • LOD of both GFAP and SI 00b were better than the clinical cut-off value of 230 pg/mL for GFAP and 470 pg/mL for SI 00b.
  • Calibration curves for the assay of cTnITC and GFAP were also performed with unprocessed whole blood with LOD of 22 and 2 pg/ml, respectively, which shows the broader application of the EC- Biosensor and its efficacy in POC settings.
  • FIG. 32A-32C show calibration curves of different biomarkers run on the EC-Biosensor using unprocessed whole blood. Y-axis shows the current density for different concentrations of biomarkers run on EC Biosensors.
  • FIG. 32A depicts a calibration curve of cTnITC;
  • FIG. 32B depicts a calibration curve of GFAP, and
  • a microfluidic device was developed with an integrated EC-Biosensor for parallel testing of six sensors (FIG. 30A and 3 OB). LOD of 14 pg/mL and 27 pg/mL was obtained for cTnITC and GFAP, respectively, using microfluidic EC-Biosensors within 15 min (FIG. 30C and 30D).
  • 28C shows no significant difference in current density between the EC-Biosensor stored for 24h at room temperature after the assay to the fresh EC-Biosensors for detection of cTnITC over the whole calibration range.
  • assay of GFAP at different concentrations was performed in four sets of EC-Biosensors in parallel and was measured on different days (1, 2, 4, and 8 days).
  • FIG. 28D no significant difference in signal was found between fresh EC-Biosensor and EC-Biosensor measured after storing in room temperature for up to 8 days, which shows that the precipitated TMB offers the flexibility of localized precipitation even under fluctuating condition and be reliably stored for at least 8 days after the completion of the assay.
  • FIG. 29B A thorough investigation of specificity and cross-reactivity of both MI and TBI biomarkers were tested against capture and detection antibodies of each of these markers.
  • FIG. 29B As shown in FIG. 29B, FIG. 33A-33C, and FIG. 34A-34D, BNP, NT-proBNP, GFAP, and SlOOb did not show any cross-reactivity with capture and detection antibody of other biomarkers.
  • Abeam anti- cTnl antibody pair showed cross-reactivity with BNP and NT-proBNP capture antibody; thus, anti- cTnlTC antibody pair which did not show any cross-reactivity with other antibodies were used for multiplexing experiments.
  • FIG. 29B As shown in FIG. 29B, FIG. 33A-33C, and FIG. 34A-34D, BNP, NT-proBNP, GFAP, and SlOOb did not show any cross-reactivity with capture and detection antibody of other biomarkers.
  • Abeam anti- cTnl antibody pair showed
  • FIG. 33A-33C illustrate the specificity and cross-reactivity test for different biomarkers of MI and TBI done in 96 well plate.
  • FIG. 33A shows the specificity and crossreactivity of NT -proBNP antigen against different capture antibody (anti-cTnITC, anti -BNP, anti- GFAP, and anti-S-lOOb) and detection antibody (anti-cTnITC, anti -BNP, anti-GFAP, and anti-S- 100b) along with specific detection with anti-NTpro BNP capture and detection antibody at different concentration of NT-proBNP.
  • FIG. 33A shows the specificity and crossreactivity of NT -proBNP antigen against different capture antibody (anti-cTnITC, anti -BNP, anti- GFAP, and anti-S- 100b) and detection antibody (anti-cTnITC, anti -BNP, anti-GFAP, and anti-S- 100b) along with specific detection with anti-NTpro BNP capture and detection antibody at different
  • 33B shows the specificity and cross-reactivity of GFAP antigen against different capture antibody (anti-cTnITC, anti -BNP, anti -NT -proBNP, and anti-S-lOOb) and detection antibody (anti-cTnITC, anti-BNP, anti -NT -proBNP, and anti-S-lOOb) along with specific detection with GFAP capture and detection antibody at different concentration of GFAP.
  • 33C shows the specificity and cross-reactivity of S- 100b antigen against different capture antibodies (anti-cTnITC, anti-BNP, anti -NT -proBNP, and anti-GFAP) and detection antibody (anti-cTnITC, anti-BNP, anti -NT -proBNP, and anti-GFAP) along with specific detection with S-lOOb capture and detection antibody at different concentration of GFAP.
  • FIG. 34A-34D illustrates a specificity and cross-reactivity test for different Troponin antibody pair and antigen done in 96 well plate.
  • FIG. 34A shows specificity and crossreactivity of cTnITC antigen against different capture antibody (anti -NT-proBNP and anti-BNP) and detection antibodies (anti -NT -proBNP and anti-BNP) along with specific detection with anti- cTnlTC capture and detection antibody from abeam at different concentration cTnITC.
  • FIG. 34A shows specificity and crossreactivity of cTnITC antigen against different capture antibody (anti -NT-proBNP and anti-BNP) and detection antibodies (anti -NT -proBNP and anti-BNP) along with specific detection with anti- cTnlTC capture and detection antibody from abeam at different concentration cTnITC.
  • FIG. 34A shows specificity and crossreactivity of cTnITC antigen against different capture antibody (anti -NT-proBNP and
  • 34B shows specificity and cross-reactivity of cTnl antigen against different capture antibodies (anti- NT-proBNP and anti-BNP) and detection antibodies (anti -NT-proBNP and anti-BNP) along with specific detection with anti-cTnl capture and detection antibody from abeam at different concentration cTnl.
  • 34C shows specificity and cross-reactivity of cTnITC antigen against different capture antibody (anti -NT-proBNP, anti-BNP, anti-GFAP, and anti-S-100) and detection antibody (anti -NT -proBNP, anti-BNP, anti-GFAP, and anti-S-lOOb) along with specific detection with anti-cTnITC capture and detection antibody from Advanced ImmunoChemical Inc at different concentration of cTnITC.
  • 34D shows specificity and cross-reactivity of cTnl antigen against different capture antibodies (anti -NT-proBNP and anti-BNP) and detection antibodies (anti-NT- proBNP and anti-BNP) along with specific detection with anti-cTnl capture and detection antibody from Advanced ImmunoChemical Inc at different concentration of cTnl.
  • each sensor's electrode was individually functionalized with specific capture antibodies (anti-cTnITC, anti-SlOOb, anti -NT-proBNP, and anti-GFAP) (FIG. 29A).
  • specific capture antibodies anti-cTnITC, anti-SlOOb, anti -NT-proBNP, and anti-GFAP
  • FIG. 29C a calibration curve of cTnITC was run on the multiplexed platform where an increase in the current density was observed, which was directly proportional to the concentration of cTnITC (FIG. 29C), while the rest of the electrodes showed no signal, which shows that there is no cross-reactivity.
  • FIG. 29D shows only the specific signal for each marker.
  • FIG. 29E shows the calibration curve of all four biomarkers in parallel.
  • Two calibration curves for cTnITC and SI 00b were run from lower to higher concentration, while the other two biomarkers, NT -proBNP and GFAP, were run from higher to lower concentration.
  • Running calibration curves in the opposite direction ensures that non-specific signals from the high concentration of biomarkers (if any) will be observed at the other end with low concentration, which may be masked if all calibration curves are run in the same direction.
  • the high specificity of antibody pair to the respective analyte was observed as no nonspecific signal was observed even at a very high concentration of other analytes.
  • the nanocomposite was stored at 4 °C and ambient temperature for up to 15 weeks. After the storage of nanocomposite for different periods, sensors were rapidly coated with nanocomposite to perform the GFAP assay. 92- 113% current response was maintained for the coating stored at 4 °C for 15 weeks, while 96- 104% current response was maintained for the coating stored at room temperature for 12 weeks compared to fresh coating for the assay of GFAP (FIG. 28E and 28F).
  • Antifouling nanocomposite developed so far have been tested only under laboratory conditions and not been commercialized, so this storage stability of the nanocomposite has enormous potential for commercialization and manufacturing in reel-to-reel format as it can be easily prepared, stored, and rapidly coated to the EC-Biosensor for developing a marketable device with reliable functioning.
  • the developed EC-Biosensors were clinically validated with 22 patient plasma samples (12 for cTnITC and 10 for GFAP).
  • the data obtained from the EC-Biosensor were compared to the data from conventional 96 well plate ELISA.
  • the values obtained from both methods were plotted in a scatter plot (FIG. 30E and 30G) where the linear regression analysis showed r 2 of 0.9848 for cTnITC and 0.9819 for GFAP, showing an excellent correlation between the EC-Biosensor and conventional assay.
  • the mean line represents the bias of the EC sensor, and the Mean ⁇ 2SD are limits of the agreement in 95% confidence interval.
  • the bias of the cTnITC EC-Biosensor was 0.02 ng/mL with Mean + 2SD and Mean - 2SD value of 0.18 ng/mL and -0.13 ng/mL, respectively.
  • a bias of the GFAP EC-Biosensor was -0.003 ng/mL with Mean + 2SD and Mean - 2SD value of 0.07 ng/mL and -0.08 ng/mL, respectively. Discussion
  • POC EC-Biosensors suffer predominantly from surface fouling via biological samples and inconvenient mass manufacturing protocol.
  • the developed frugal EC-Biosensor coating process enables stable antifouling properties through a rapid and high-throughput process which could be easily translated into reel-to-reel mass manufacturing process.
  • the coated gold electrodes retained more than 88% of current density for up to 9 weeks of incubation in unprocessed human plasma.
  • nanocomposite coating could be stored at room temperature for at least 12 weeks with 96-104% current response demonstrating their long-term stability.
  • Anti-fouling nanocomposite preparation The BSA/prGOx/GA anti-fouling nanocomposite was prepared by mixing 8 mg/mL of pentaamine functionalized reduced graphene oxide (prGOX) (Millipore Sigma, no. 806579) with 5 mg/mL (IgG-Free, Protease-Free, Bovine Serum Albumin) (Jackson ImmunoResearch, no. 001-000-162) in 10 mM phosphate-buffered saline solution (PBS, pH 7.4) (Sigma Aldrich, USA, no. D8537). A similar method was used to prepare the coating with amine-functionalized reduced graphene oxide (Sigma Aldrich, USA, no. 805432).
  • prGOX pentaamine functionalized reduced graphene oxide
  • PBS pH 7.4
  • the solution was sonicated in a tip sonicator for 30 min using 1 s on/off cycles at 50 % amplitude, 125 W and 20 kHz (Bransonic, CPX 3800) followed by heating (Labnet, no. DI 200) at 105 °C for 5 min to denature the protein.
  • the resulting opaque black mixture was centrifuged at 16.1 relative centrifugal force for 15 min to remove the excess aggregates.
  • the semi-transparent nanocomposite supernatant solution was then mixed with 70% glutaraldehyde (Sigma Aldrich, USA, no. G7776) for crosslinking in the ratio of 70:2.
  • the gold electrode chips were custom fabricated using a standard photolithography process and purchased from Telic Company. Briefly, the gold wafer was deposited with 12-15 nm of chromium followed by 100 nm of gold over it. Inner electrodes were 0.448 mm in diameter (surface area of 0.1576 mm 2 ) while reference electrodes diameter was 1.15 mm in diameter (surface area of 1.038 mm 2 ). Before coating the chip with nanocomposite, chips were cleaned by sonicating in acetone (Sigma Aldrich, USA, no. 650501) for 10 min followed by isopropanol (Sigma Aldrich, USA, no. W292907) for another 10 min to remove the photoresist. To ensure that the surface of the chips is clean, the chips were then treated with oxygen plasma using a Zepto Diener plasma cleaner (Diener Electronics, Germany) at 0.5 mbar and 50% power for 2 min.
  • acetone Sigma Aldrich, USA, no. 650501
  • isopropanol Sigma Al
  • nanocomposite solution was prepared with different concentrations of BSA ranging from 0.5 mg/mL to 10 mg/mL with 3 different ratios of BSA & GA (1:70, 2:70, and 4:70). The chips were coated with these solutions for 45s at 85 °C followed by washing and electrochemical analysis.
  • nanocomposite was prepared with 5 mg/mL BSA with different concentration of prGOx (0.5, 1, 2, 4, 8, 10, 12, 15 mg/mL) with GA/prGOx/BSA of 2:70. Electrochemical analysis was done after quenching the reaction with IM ethanolamine for 30 min, followed by 1 hr incubation in 1 % BSA.
  • Rapid antifouling coating recipe combined with extensive assay development helped in significant improvement of the EC-Biosensor performance as demonstrated by the increased sensitivity and wide dynamic and linear range of the EC-Biosensor.
  • the porous BSA backbone of the matrix prevents non-specific protein adsorption but allows diffusion of electroactive soluble species.
  • prGOx which is highly conductive, accelerated electron transfer and enhanced the transduction properties.
  • developing the optimized conditions of each component of the sandwich assay led to enhancing the current response, resulting in highly sensitive immunoassays.
  • EC-Biosensor also showed excellent correlation with reported values in clinical samples and thus has huge potential for commercial POC detection.
  • gold electrodes covered with nanocomposite were analyzed by CV in PBS containing 5 mM [Fe(CN)6] 3 ' /4 ‘ at 200 mV/s between -0.5 to 0.5V.
  • bare gold electrodes and gold electrodes covered with nanocomposite were analyzed by CV in PBS containing 5 mM [Fe(CN) 6 ] 3 ' /4 ‘ by increasing the scan rate from 10 to 1000 mV/s between -0.5 to 0.5V.
  • Spectroscopic/Microscopic study of gold electrode/ anti-fouling nanocomposite The nanocomposites along with intermediate components were characterized by UV spectroscopy (Nanodrop 2000C, Thermo Scientific) after the addition of every component, to elucidate changes in the absorbance bands of the peptide backbone or the aromatic rings due to the crosslinking of BSA and GOx with GA. Topographic characterization for the nanocomposite and other coatings over the sensor was carried out by SEM (Verios G4 XHR, Thermo Fisher Scientific). The samples were first coated with a thin layer of approximately 6 nm Cr by sputtering (K755X EM Technologies LTD.).
  • Imaging was carried out by detection of secondary electrons using an in-lens detector at an accelerating voltage of 5 kV.
  • samples were prepared using the in-situ FIB lift-out technique on an FEI Helios 650 Dual Beam FIB/SEM. The samples were capped with sputtered Ir, protective carbon and e-Pt/I-Pt before milling. To obtain better contrast of the coating one set of TEM was done without Ir. The TEM lamella thickness was -lOOnrn. The samples were imaged with an FEI Tecnai Talos FEG/TEM operated at 200kV in bright-field (BF) TEM mode and high-resolution (HR) TEM mode.
  • BF bright-field
  • HR high-resolution
  • AFM images were collected using a Dimension Icon AFM instrument (Bruker, Santa Barbara, California, USA). The instrument was calibrated against a NIST traceable standard. Soft Tapping Mode was used as analysis mode with OTESPA-R3 (Bruker) as AFM probe. 1 st order flattening was used for data post-processing. One 1 pm x 1 pm area was imaged near the center of each sample. AFM 2D and 3D height images were obtained along with the roughness measurements of gold and gold/coating. The topography differences of these images are presented in colors where the brown is low and the white is high. The z ranges are noted on the vertical scale bar on the right side of the images.
  • Max height (Rmax) is the difference in height between the highest and lowest points of the surface relative to the Mean Plane.
  • Surface area is the area of the 3 -dimensional surface of the imaged area. It was calculated by taking the sum of the areas of the triangles formed by 3 adjacent data points throughout the image.
  • X-ray Photoelectron Spectroscopy (XPS) was used to determine semi-quantitative atomic composition and chemistry using PHI Quantum 2000 instrument.
  • Monochromated Alka a 1486.6eV was used as X-ray source with an acceptance angle of ⁇ 23°, take-off angle of 45°, and analysis area of 1400 pm * 300 pm.
  • TOF-SIMS was performed using IONTOF TOF-SIMS 5 instrument and data were obtained using a liquid metal ion gun (LMIG) primary ion source. Both surface spectrum and depth profile were acquired from the sample.
  • LMIG liquid metal ion gun
  • Ar-cluster was used as ion source with Ion beam potential of 2.5 keV on an area of 500 pm x 500 pm for sputtering.
  • Bis + was used as ion source with Ion beam potential of 30 keV on an area of 200 pm x 200 pm for analysis.
  • the data are presented as mass spectra which are displayed as the number of secondary ions detected (Y-axis) versus the mass-to- charge (m/z) ratio of the ions (X-axis).
  • the ion counts are shown on linear intensity scales, and probable empirical formulae for several peaks are identified in the figures.
  • detection antibody was diluted to Img/mL in PBS followed by addition of 1 ql of modifier/10 ql of antibody and mixed to the linker for 30 min and finally, the reaction was quenched by adding 1 ql of quencher/10 qL of solution.
  • the biotin-conjugated antibody was ready to be used after 5 min.
  • 1 mg/mL of anti-cTnl capture antibody was spotted to three working electrodes and BSA on fourth as anegative control.
  • NT-proBNP Medix Biochemica, no. 610090
  • NT-proBNP detection antibody Medix Biochemica, no. 100712
  • chips were spotted with 500 pg/mL of anti-cTnl capture antibody.
  • Three different concentrations of cTnl (0, 0.1, and 10 ng/mL) was mixed with different concentrations of the biotinylated anti-cTnl detection antibody (final concentration of 1, 2, 3, 5, and 8 pg/mL) in the ratio of 9:1 and 15 pL was added to each chip. Chips were washed after 30 min followed by the addition of Poly-HRP-Streptavidin for 5 min and TMB for 1 min before reading. For optimization of Poly-HRP-Streptavidin chips were spotted with 500 pg/mL of anti-cTnl capture antibody.
  • cTnl Different concentrations of cTnl (0, 0.01, 0.05, 0.1, 0.5, 1, and 10) were mixed with 5 pg/mL biotinylated anti-cTnl detection antibody and incubated on the chip for 30 min. 5 ug/mL of Poly- HRP-Streptavidin was added for 5 min followed by washing. One set of chips were incubated for 1 min with precipitating TMB while the other set was incubated for 5 min before washing and reading the chips. For all the subsequent experiments optimized conditions of 500 pg/mL of capture antibody, 5 pg/mL of Poly-HRP-Streptavidin, and 2 min of TMB precipitation time were used and only the concentration of detection antibody was optimized.
  • chips were spotted with 500 ug/mL of anti-BNP capture antibody (HyTest, no. 50Elcc).
  • chips were spotted with 500 ug/mL of anti -NT-proBNP capture antibody.
  • Three different concentrations (0, 0.1, and 10 ng/mL) of NT-proBNP were mixed with different concentrations (1, 3, 6, and 9 pg/mL) of the biotinylated anti -NT-proBNP detection antibody in the ratio of 9:1 and 15 pL was added to each chip. Chips were washed after 30 min followed by the addition of Poly -HRP- Streptavidin for 5 min and TMB for 2 min before reading.
  • chips were spotted with 500 ug/mL of anti-cTnl capture antibody (Advanced ImmunoChemical, no. 2-TIC-rc).
  • Three different concentrations (0, 0.01, and 1 ng/mL) of cTnITC complex (HyTest, no. 8T62) was mixed with different concentrations (1, 3, 6, and 9 pg/mL) of biotinylated anti-cTnITC detection antibody (Advanced ImmunoChemical, USA no. 2-TC) in the ratio of 9: 1 and 15 pL was added to each chip. Chips were washed after 30 min followed by addition of Poly -HRP-Streptavi din for 5 min and TMB for 2 min before reading.
  • Detection of Biomarkers using the EC-Biosensor Detection of all the biomarkers was done on the chip using the optimized conditions. Three working electrodes were spotted with a capture antibody concentration of 500 pg/mL diluted in PBS. Anti-GFAP capture antibody (HyTest, no. GFAP83cc) and anti-SlOOb capture antibody (HyTest, no. 8B10cc) were used for the assay of GFAP (HyTest, no. 8G45) and SI 00b (HyTest, no. 8S9h), respectively.
  • Detection of Biomarkers using 96 well colorimetric assay For 96 well assay of the biomarkers, 100 pL of 1 pg/mL capture antibody prepared in carbonate-bicarbonate buffer at pH 9.2 was added to NUNCTM MAXISORPTM ELISA plates (BioLegend, no. 423501) and incubated overnight at 4 °C. The plates were washed 3 times with 200 pL of PBST followed by the addition of 200 pL of 2.5 % BSA for Ih. After washing the plates 100 pL of different concentrations of the biomarkers (1% buffer/plasma) were added and incubated at 400 rpm for Ih.
  • biotinylated detection antibody (0.5 pg/mL for cTnl, NT-proBNP, cTnITC, and GFAP and 1 pg/mL for BNP and SlOOb) was added for Ih before washing and adding 100 pL of Streptavidin- HRP (1:200 dilution in 0.1 % BSA).
  • the plate was washed and 150 pL of turbo TMB (Thermo Scientific, no. 34022) was added for 20 min followed by the addition of 150 pL of Stop solution to stop the reaction.
  • the plate was immediately read using a microplate reader at 450 nm.
  • samples were diluted 1: 1 in 1 % BSA.
  • Specificity of Antigen and Antibody for MI and TBI using 96 well colorimetric assay Specificity of Antigen and Antibody was performed in 96 well ELISA plates. For each biomarker, four different concentrations were run with specific antibody pair to observe the signal for specific binding. To see if there is any non-specific binding of antigen to capture antibody of other biomarkers, all the non-specific capture antibodies were coated to the plates followed by the addition of high concentration analyte (10 ng/mL) and negative control (0 ng/ml) and detection antibody for the analyte. To test non-specific binding between the antigen and detection antibody of other biomarkers, specific capture antibody was coated to the plate and high concentration and negative control were added to the plate followed by non-specific detection antibody.
  • BNP specificity test four concentrations of BNP (0, 0.1, 1, and 10 ng/mL) were tested with specific antibody pair for BNP.
  • non-specific capture antibody-antigen binding test four different capture antibodies (anti -NT -proBNP, anti-cTnl, anti- GFAP, and anti-SlOOb) were coated at 1 pg/mL followed by addition of either 10 ng/mL or 0 ng/mL of BNP. After washing anti-BNP detection antibody was added followed by Streptavidin- HRP and TMB.
  • non-specific antigen-detection antibody binding test BNP capture antibody followed by 0 or 10 ng/mL of BNP was added. After washing, non-specific biotinylated detection antibodies (anti-NT-proBNP, anti-cTnl, anti-GFAP, and anti-SlOOb) were added followed by Streptavidin-HRP and TMB. Likewise, specificity test for other biomarkers including NT-proBNP, GFAP, and SI 00b was done similarly with specific and non-specific antigen-antibody pair. Likewise, for cTnl and cTnITC specificity test was performed with both abeam antibody pair (specific to cTnl) and Advanced ImmunoChemical antibody pair (specific to cTnITC).
  • Increasing concentration of cTnITC and SI 00b and decreasing concentration of GFAP and NT -proBNP (0.01 cTnITC & SlOOb + 10 GFAP & NT-proBNP; 0.05 cTnITC & SlOOb +1 GFAP & NT-proBNP; 0.1 cTnITC & SlOOb + 0.1 GFAP & NT-proBNP; 1 cTnITC & SlOOb + 0.05 GFAP & NT-proBNP; 10 cTnITC & SlOOb + 0.01 GFAP & NT-proBNP) was mixed with all four biotinylated detection antibody and incubated for 30 min. Chips were washed and Poly-HRP-Streptavidin was added for 5 min followed by TMB for 2 min before washing and reading the chips.
  • the microfluidic chip has several inlet and outlet ports and is covered with a special arrangement of cover and adhesive tapes to attach the sensor on top of the microfluidic chip. These tapes also define the flow channel between the sensor and the microfluidic chip (FIG. 30A and 30B).
  • the microfluidic chip was fabricated via 3D printing (Tiger APEX pro XHD 3D printer, Tiger 3D & Romanoff Int. Amityville, NY, USA). A clear photopolymer resin with low viscosity was used to fabricate the microfluidic chip (Tiger3D Clear 78-5011-L, Tiger 3D & Romanoff Int.
  • a double-sided adhesive tape was used to bond the sensor to the microfluidic chip and to pattern the sidewalls of the microfluidic channel sandwiched between them (ARSEALTM90880 Polypropylene Double-Sided Adhesive Tape, Adhesive research Inc., Glen Rock, PA, USA).
  • the flow was initiated by peristaltic microfluidic pumps (RP-QII, Tagasako, Nagoya, Japan) driven by H-bridge brushed motor drivers (Pololu, Las Vegas, NV, USA).
  • the pumps were controlled by a microcontroller (Arduino Uno, iOS, Turin, Italy) via pulse density modulation to allow for high flow resolution at low pump speeds.
  • the pump system was commanded through an LCD/keypad interface (Adafruit, New York, NY, USA).
  • the sample mixed with detection antibody 40 pl was added to inlet wells at the flow rate of 5 pl/min for 8 min.
  • An optimized condition of detection antibody as discussed earlier was used.
  • 25 pl of strep-HRP was then added at 5 pl/min for 5 min.
  • 20 pl of TMB was added at 20 pl/min for 1 min and incubated under static incubation for 2min.
  • PBST wash was done after each step at 20 pl/min for 1 min.
  • FIG. 27C shows the optimization of the concentration of Streptavidin-poly HRP as 5 pg/mL and also shows that higher concentrations of HRP may lead to a thick layer of TMB which can have an insulating effect ultimately decreasing the signal.
  • TMB precipitation time for TMB can increase the resulting signal ultimately increasing the sensitivity of the assay but over precipitation of TMB can lead to an insulating effect decreasing the output signal.
  • 2 min of TMB precipitation time was considered as optimum TMB precipitation time as it could detect lower concentrations of cTnITC (0.05 ng/mL and 0.01 ng/mL) where 1 min did not show any signal.
  • FIG. 27E shows the optimization of the BNP detection antibody as 15 pg/mL as it gave the highest signal to noise ratio without any background noise (0 ng/mL).
  • FIG. 27F shows the optimization of NT-proBNP detection antibody as 6 pg/mL. The concentration of detection antibody higher than 6 pg/mL showed background signal. Finally, 6 pg/mL was considered as optimum cTnITC detection antibody concentration as shown in FIG. 27G.
  • FIG. 27A shows specific signal for BNP as increasing intensity of signal with increasing concentration of BNP (black dots). Even a high concentration of 10 ng/mL of BNP showed a similar signal as 0 ng/mL of BNP with all other non-specific capture or detection antibody which shows that there was no non-specific binding with capture or detection antibody for (cTnl, NT-proBNP, cTnITC, GFAP, & SlOOb).
  • FIG. 27A shows specific signal for BNP as increasing intensity of signal with increasing concentration of BNP (black dots). Even a high concentration of 10 ng/mL of BNP showed a similar signal as 0 ng/mL of BNP with all other non-specific capture or detection antibody which shows that there was no non-specific binding with capture or detection antibody for (cTnl, NT-proBNP, cTnITC, GFAP, & SlOOb).
  • FIG. 33A shows specificity of NT-proBNP and similar to BNP it only shows the specific signal for NT-proBNP and all other non-specific capture and detection antibody shows signal similar to 0 ng/mL even at high concentrations.
  • FIG. 33B and 33C show the specificity test for GFAP and SI 00b where only the specific signal can be observed. All the non-specific capture and detection antibodies showed signals similar to 0 ng/mL showing there is no cross-reactivity or non-specific binding.
  • FIG. 34A abeam anti-cTnl could only detect up to 10 ng/ml of cTnITC, rest concentration showed similar a signal with non-specific capture/detection antibody as abeam antibody has epitope against cTnl and not cTnITC complex.
  • FIG. 34B shows abeam anti-cTnl antibody pair can specifically detect cTnl but has high cross-reactivity with BNP and NT-proBNP capture antibody and thus cannot be used in a multiplex setting with those biomarkers.
  • AIC Advanced Immunochemical Inc.
  • FIG. 34C shows a specific signal for cTnITC with the increase in signal from 0 ng/mL to 10 ng/mL.
  • the non-specific signal was very minimum thus AIC antibody pair and cTnITC will be used for all further multiplex detection.
  • all these biomarkers BNP, NT- proBNP, cTnITC, GFAP, and SI 00b can be used for multiplexed detection.
  • the term “consisting essentially of' refers to those elements required for a given embodiment. The term permits the presence of elements that do not materially affect the basic and novel or functional characteristic(s) of that embodiment of the claimed invention. [00222] The term “consisting of' refers to compositions, methods, and respective components thereof as described herein, which are exclusive of any element not recited in that description of the embodiment.

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EP21907436.6A 2020-12-17 2021-11-29 Anwendungen, verfahren und werkzeuge zur entwicklung, schnellen herstellung und abscheidung einer nanokompositbeschichtung auf oberflächen für diagnosevorrichtungen mit elektrochemischen sensoren Pending EP4263728A1 (de)

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